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U.S Fish & Wildlife Service
A Guide to Nestling
Development and Aging
in Altricial Passerines
Biological Technical Publication
BTP-R6008-2007
U.S Fish & Wildlife Service
A Guide to Nestling
Development and Aging
in Altricial Passerines
Biological Technical Publication
BTP-R6008-2007
Dennis Jongsomjit1
Stephanie L. Jones2
Thomas Gardali1
Geoffrey R. Geupel1
Paula J. Gouse3
1 PRBO Conservation Science, Petaluma, CA
2 U.S. Fish and Wildlife Service, Region 6, Office of Migratory Birds,
Denver, CO
3 U.S. Fish and Wildlife Service, Bowdoin National Wildlife Refuge,
Malta, MT
Cover images: Top: Crissal Thrasher, Toxostoma crissale
Bottom: Brewer’s Sparrow, Spizella breweri
Photo credits: Top: Chris McCreedy/PRBO
Bottom: Colin Wooley/PRBO
ii A Guide to Nestling Development and Aging in Altricial Passerines
Author contact information:
Dennis Jongsomjit
PRBO Conservation Science
3820 Cypress Drive
Petaluma, CA 94954
707-781-2555
email:djongsomjit@prbo.org
Stephanie L. Jones
U.S. Fish and Wildlife Service, Region 6
Nongame Migratory Birds
P.O. Box 25486 DFC
Denver, CO 80225
303-236-4409
Email: stephanie_jones@fws.gov
Thomas Gardali
PRBO Conservation Science
3820 Cypress Drive
Petaluma, CA 94954
415-868-0655 x 381
Email: tgardali@prbo.org
Geoffrey R. Geupel
PRBO Conservation Science
3820 Cypress Drive
Petaluma, CA 94954
415-868-0655 x 301
Email: ggeupel@prbo.org
Paula J. Gouse
U.S. Fish and Wildlife Service
Bowdoin National Wildlife Refuge
194 Bowdoin Auto Tour Rd
Malta, MT 59538
406-654-2863
Email: paula_gouse@fws.gov
For additional copies or
information contact:
U.S. Fish and Wildlife Service, Region 6
Nongame Migratory Bird Program
P.O. Box 25486 DFC
Denver, CO 80225-0486
Recommended citation:
Jongsomjit, D., S. L. Jones, T. Gardali, G. R.
Geupel, and P. J. Gouse. 2007. A guide to nestling
development and aging in altricial passerines. U.S.
Department of Interior, Fish and Wildlife Service,
Biological Technical Publication, FWS/BTP-R6008-
2007, Washington, D.C.
Table of Contents iii
Table of Contents
List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Nestling Growth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Analyzing Growth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Growth Patterns and Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Aging Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Variables Used for Aging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Individual feather tracts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Wing chord. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Tarsus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Primary and rectrices pin lengths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Culmen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Eyes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Longest broken primary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Total body length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Gape and rictus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Physical and behavioral descriptors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Using the Species Accounts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Measurements and Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Feather definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Tarsus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Wing chord. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Primary and rectrix pin length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Culmen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Total length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Longest broken primary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Gape and rictus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Physical and behavioral descriptors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Species Account Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Species information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Indicator table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
General feather development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Key visual indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Photographs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Feather tract data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Morphometric data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
General description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Species Accounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Dusky Flycatcher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Carolina Wren. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Wrentit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Sprague’s Pipit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Song Sparrow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Chestnut-collared Longspur. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
American Goldfinch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Appendix A. Adult Morphometric Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Appendix B. Data Collection Methods and Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
iv A Guide to Nestling Development and Aging in Altricial Passerines
List of Figures
Figure 1. Dorsal and ventral views of a nestling with the individual feather tracts marked and identified. . . . .5
Figure 2. Tarsus with measurement indicators at the tibiotarsus joint and distal end of the last leg scale . . 6
Figure 3. Wing chord as measured with a wing ruler, without flattening or pressing down on the wing .. . . . . 6
Figure 4. Pin lengths as measured from the point of emergence from the skin . . . . . . . . . . . . . . 6
Figure 5. The culmen as measured from nares to tip . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 6. Total body length taken from the tip of the bill to the tail bud . . . . . . . . . . . . . . . . . 6
Figure 7. The exposed portion of the longest broken primary as measured with a ruler. . . . . . . . . . . . . . . . . . . .6
Figure 8. The gape as measured with calipers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Figure 9. Examples of feather development and appearance using a Wrentit on Day 7 . . . . . . . . . . 7
Figure B-1. An example of systematic labeling of data sheets and photographs which uniquely identifies
each nestling and their age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Acknowledgments v
Acknowledgments
The collection of data for this guide would not have
been possible without the help of many interns and
field biologists including Parvaneh C. Abbaspour,
Bethany S. Atchley, Amon J. Armstrong, Ross R.
Conover, Gerhard A. Epke, Tristan R. Gingerich,
Geetha M. Jayabose, Scott F. Jennings, Laura H.
Kaplan, Errin B. Kramer-Wilt, Ben G. Larson,
Blaine MacDonald, Emily Morrison, Henry
Ndithia, Kerry E. Neijstrom, Alexander Rosenthal,
Corrina Snow, Amanda B. Shults, and Dionne R.
Wrights. Many thanks to Suzanne Austin-Blythell,
Bruce Barbour, Thomas M. Haggerty, Steve N. G.
Howell, and Diana L. Humple for providing helpful
comments to earlier drafts of this guide. Fig. 1 is
adapted from Gill (1994) and Fig. 6 is adapted from
Baldwin et al. (1931). We thank Peter Pyle and
Steve N. G. Howell for graciously allowing us the
use of Figs. 2, 3, and 5 (Pyle 1997). Figures 4, 7, and
8 were drawn by Dennis Jongsomjit. We thank the
Point Reyes National Seashore for their continued
cooperation. Funding was provided by the U.S. Fish
and Wildlife Service Region 6 Nongame Migratory
Bird Program. This is PRBO contribution 1603.
Data Contributors
We especially thank the colleagues that contributed
nestling data to this publication: Ryan Burnett and
Vanessa Tissdale – PRBO Conservation Science,
Dusky Flycatcher (Empidonax oberholseri) and
Thomas M. Haggerty – Department of Biology,
University of North Alabama, Carolina Wren
(Thryothorus ludovicianus).
1
Nestling growth and development studies have
been a topic of interest for a greater part of the
last century (Sutton 1935, Walkinshaw 1948)
and continue to be of interest today. This is not
surprising since studies on nestling growth can
provide a wealth of biological information that
has larger implications for avian management
and conservation. Despite this history of studying
nestling development, basic information is still
limited or absent for many species. Many questions
remain unanswered, and contradictory conclusions
are often found in the literature (Starck and Ricklefs
1998a). Therefore, much information on aging and
development can still be gained from studying the
development patterns of similar species and from
comparative studies, across avian orders (Minea
et al. 1982, Saunders and Hansen 1989, Carsson
and Hörnfeldt 1993). Additionally, nestling growth
studies can yield insight into the effects of different
nesting strategies on productivity (O’Connor
1978), as well as the impacts of parental effort and
environmental variables on fitness (Ross 1980,
Ricklefs and Peters 1981, Magrath 1991). Since low
reproductive success may play a significant role in
the declines of many North American passerines
(Sherry and Holmes 1992, Ballard et al. 2003), a
better understanding of the factors that influence
reproductive success is a vital component of avian
conservation (Martin 1992). Data on nestling aging
can be used to improve nest survival estimates
(Dinsmore 2002, Nur et al. 2004), providing
information that can be used to more precisely age
nests (Pinkowski 1975, Podlesack and Blem 2002),
(Jones and Geupel 2007). Indeed, the relatively short
time period young spend developing in the nest is
a critical part of a bird’s life cycle and a nestling’s
developmental path can affect its survival to
independence, its survival as an adult, and its future
reproductive success.
Nestling Growth
Ornithologists categorize birds over an altricial to
precocial spectrum, based on differences in the rate
of growth and type of development young birds will
undertake (Starck and Ricklefs 1998b). Placement
into this spectrum depends on various broad
characteristics such as mobility, feeding behavior,
presence of down, and parental nest attendance (Gill
1994). Growth rates are highly variable within the
altricial to precocial spectrum, with developmental
periods varying as much as 30-fold (Ricklefs 1983).
Much of this variation in growth can be attributed, at
the phylogenetic level, to differences in body mass.
In general, altricial species can grow at 3-4 times the
rate of precocial species, and growth rates of birds
with similar mass can vary by as much as a factor of
10 (Ricklefs et al. 1998). In this guide, we focus on
altricial species.
Nestling growth variability has largely been studied
looking at effects on individual fitness of offspring
and parents (e.g., Murphy 1983, Magrath 1991,
Halupka 1998). Differences between populations can
manifest as morphological differences or differential
timing in the growth and maturation of certain body
components (Murphy 1983, Burns 1993). However,
the growth rate of a single species throughout its
entire range can sometimes vary little (King and
Hubbard 1981, Murphy 1983, Pereyra and Morton
2001).
Variability in nestling growth rates can be due to
many ecological factors, in conjunction with specific
species life history strategies; some developmental
processes might be linked and are also independent
of the nutritional state of a nestling (Ricklefs
1968a). Some factors associated with species specific
growth rates and patterns include nest location,
synchronicity of hatching, and brood size (Murphy
1983). Ecological factors that influence nestling
growth are generally related to limitations in food
availability (Ricklefs 1993), including weather
(Petersen et al. 1986), habitat differences and quality
(Ross 1980, Dawson and Bidwell 2005), parasites
(Burhans et al. 2000), competition between nest
mates (Werschkul and Jackson 1979, Ricklefs 1982),
and parental abilities (Briskie 1995). Additionally,
higher nest-predation rates may favor higher
nestling growth rates (Lack 1968, Remes and Martin
2002, but see Ricklefs 1969).
At the physiological level, an important factor
thought to limit growth is “tissue level constraint”,
where nestlings are growing at a maximum rate
allowable by the tradeoff existing between resources
available for growth and mature tissue function
(Ricklefs et al. 1998). Once certain types of cells
differentiate into mature functioning tissue, they
no longer continue to grow (O’Connor 1984). After
a period of below normal growth, a nestling would
need to increase its growth rate in order to “catch
up” to its normal developmental timing. However,
such compensatory growth has not been shown to
occur in altricial birds (Schew and Ricklefs 1998,
Lepczyk and Karasov 2000; but see Remes and
Martin 2002, Bize et al. 2006). In one study, addition
of body mass and growth rates in overfed young in
the laboratory did not differ from that of wild young
Introduction
Introduction
2 A Guide to Nestling Development and Aging in Altricial Passerines
(Konarzewski et al.1996). These results indicate that
young may be growing at the maximum rate allowed
by cell function and physiology.
Analyzing Growth
An important part of visualizing and analyzing
nestling growth is the use of fitted growth equations
(Ricklefs 1967, 1983). When fitted into a growth
equation, using non-linear regression, three
components of growth are provided: the rate,
magnitude, and form of growth. When graphed,
nestling growth is often shown to increase, reach
a peak, and finally level off in a sigmoidal shape.
These equations simplify and allow for comparative
analysis of growth between and within species.
Information on adult body weight and size are
also an important aspect of analyzing growth with
these equations (O’Connor 1984); adult body size
measurements are provided for the study species in
this guide (Appendix A). Alternatively, growth data
can also be used to build predictive models of age
(Holcomb and Twiest 1971, Hamel 1974).
Growth Patterns and Aging
Inherent species specific patterns of growth and
development can often be used to age nestlings
(Starck and Ricklefs 1998a). In nestling growth
patterns, each body component can begin growth
at a different point in time relative to other
components, resulting in a staggered growth
pattern. Specific patterns in this type of growth
are generally adaptations for nest survival. For
example, in some species, contour feathers tend to
rapidly grow and unsheathe before the remiges,
providing important insulation cover early in life,
when young cannot self-thermoregulate (Murphy
1981). In another example, growth of the tarsus or
gape, important for food acquisition, may proceed
rapidly during the early nestling stage (O’Connor
1984). Besides growth, developmental events
(e.g., pin-feather eruption patterns, eye opening,
and behavior) can be age specific and are readily
observed (Ricklefs 1966, Murphy 1981). Thus, using
a combination of several growth measurements
can provide reliable aging throughout the nestling
period (King and Hubbard 1981, Murphy 1981,
Haggerty 1994, Podlesak and Blem 2002).
Aging Recommendations
The type and number of measurements needed
for reliable aging may vary among species but
preliminary analysis of our data shows that wing
length, tarsus length, weight, and culmen provide
good predictive models of age. Since nestlings may
be growing at a maximized rate, age estimates can
be informed by considering the development of the
most advanced nestlings, and by using more than
one nestling. In nests parasitized by Brown-headed
Cowbird (Molothrus ater), where all the young
may be receiving less food than normal, aging host
young may or may not be reliable (Kilner et al. 2004,
Weatherhead 1989). Aging of the Brown-headed
Cowbird young may be possible, depending on the
host species (Scott 1979, Kilpatric 2002).
With any aging technique, it is important to be
aware that deviations from normal growth and
development can occur, preventing accurate
predictions of age for those individuals.
Data from known age nests can bring attention
to abnormal developmental patterns and rates
in the local populations. Measuring nestlings on
more than one day can also reveal deviations from
normal development. Energy restrictions can be a
source of another type of staggered growth where
nestlings are forced to allocate resources to areas
of development more important to their survival
(Oyan and Anker-Nilssen 1996, Dahdul and Horn
2003). This could result in some body components
growing normally, while others slow or stop growing
completely (Boag 1987, Lepczyk and Karasov 2000).
Feather developmental events in particular, such as
pin feather eruption, may proceed normally, despite
abnormal growth in other body components (Schew
and Ricklefs 1998). Hence, though measuring
several variables may help reduce aging error, if any
abnormal patterns are identified individuals should
be aged with caution.
Variables Used for Aging
Several measurements of growth have been widely
used in the literature. We have attempted to be as
inclusive as possible with the variables used in this
guide. Given the time restrictions of measuring
young, we have narrowed the variables to those that
proved useful in the literature and in field trials.
Individual feather tracts.––The developmental
timing of feather tracts tends to follow a consistent
age related pattern within a species and are the
most easily noted traits when examining nestlings.
The flight feathers will often begin to emerge and
develop in pin before the contour feathers; however,
contour feathers will often begin to unsheathe
before the flight feathers (Murphy 1981). Feather
development may proceed independently of growth
in body size or mass gain (Ricklefs 1968a). These
qualities make feather development an important
component of aging nestlings.
Wing Chord.––Wing chord is another simple
measurement that is reported often in the literature.
As part of staggered development, wing growth can
proceed quickly throughout the nestling stage and
has been shown to provide a good estimate of age
(Ricklefs 1975, Haggerty 1994, McCarty 2001).
Weight.––Data on mass gain is the most common
data published on nestling growth. This may be, in
part, because it is a relatively easy measurement
to take. Though nestlings may gain mass at rapid
levels, mass gain may be more sensitive than other
parameters to food availability or environmental
stress and may not always reflect the maturity level
of a nestling (Boag 1987, Lepczyk and Karasov
2000). In some species, such as aerial foragers and
cavity nesters, mass may even reach an asymptotic
peak above normal adult weight, and then diminish
to normal levels before fledging (Ricklefs 1968b).
For these reasons, mass should not be used alone to
3
indicate age. Nevertheless, its wide availability in
the literature makes mass a practical component of
nestling aging.
Tarsus.––Tarsus length may grow normally even
with food restrictions (Best 1977, Lepczyk and
Karasov 2000). The tarsus is also a part of the
staggered development seen in nestlings. For
example, in the Bachman’s Sparrow (Aimophila
aestivalis), the tarsus was shown to grow quickly
during the early part of the nestling stage before
tapering off after day 5 (Haggerty 1994).
Primary and rectrix pin lengths.––Flight feather
growth proceeds quickly and may be affected by
factors different from those that affect mass gain
(Murphy 1985). Also, growth of the remiges may
not be as erratic as weight gain, making it a more-reliable
age indicator (King and Hubbard 1981, Boag
1987). While primary pins usually grow rapidly, in
some species this growth may begin to slow down
and in some cases length may reach a maximum late
in the nestling period. Rectrices, on the other hand,
usually do not begin to develop until the latter half
of the nestling period, where they proceed to grow
rapidly. This division in growth schedule allows
one to measure rapidly growing flight feathers
throughout the nestling stage.
Culmen.––The culmen can serve as a good age
indicator since it may grow normally despite food
restrictions (Lepczyk and Karasov 2000). For
many species, the culmen is also a relatively simple
measurement to take.
Eyes.––Nestlings will often begin to open their eyes
at a predictable age. Thus, this event can serve to
reinforce age estimates. The date the eyes begin
to open is especially useful, while the degree of eye
opening can vary considerably.
Longest broken primary.––The degree of exposed
primary feather is a development process that may
proceed independent of growth and can be used to
reinforce nestling age estimates.
Total length.––Total length is historically an
important standard measurement (Baldwin et al.
1931) that is relatively simple and quick to take.
However, the length can increase quickly, and should
be used with caution. The position of the young can
reduce or increase this measurement dramatically.
Gape and rictus.––The gape can grow quickly
early in the nestling period. However, the rictus
(soft tissue at base of bill) is very pliable during
growth, and measurements of the gape can increase
or decrease greatly between days as the rictus
contracts and expands. Hence, it should be both
measured and used with caution.
Physical and behavioral descriptors.––Because
certain behavioral events can consistently occur at a
specific age and are easily noted (Ricklefs 1966), they
are an important part of aging the young. They can
also prove useful in narrowing age determination
when growth data places the age of the nestling
within a certain range.
Yellow-breasted chat (Icteria virens). Chris McCreedy/PRBO
Introduction
4 A Guide to Nestling Development and Aging in Altricial Passerines
We had two primary objectives in writing this
guide, to report and promote research on species
specific patterns of altricial passerine nestling
development and aging, and to achieve better
estimates of nestling ages. We present nestling
data on seven species of altricial passerines: Dusky
Flycatcher (Empidonax oberholseri), Carolina Wren
(Thryothorus ludovicianus), Wrentit (Chamea
fasciata), Sprague’s Pipit (Anthus spragueii), Song
Sparrow (Melospiza melodia), Chestnut-collared
Longspur (Calcarius ornatus), and American
Goldfinch (Cardeulis tristis). In addition, nestling
data collection techniques have been highly variable,
limiting the potential for data sharing, limiting
comparisons across species and families, and limiting
the use of data in combined analyses. Therefore, we
present suggestions for standardizing the collection
of nestling data in Appendix B.
Objectives
5
Using the Species Accounts
In the species accounts we report detailed
information on species-specific nestling
development. A primary goal in the design of the
accounts was to make them as useful as possible
for those interested in aging nestlings. The first
page of each account begins with life history
information for the particular species. This is
followed immediately by tables listing distinguishing
developmental criteria (i.e., appearance) and general
feather development patterns throughout the
nestling period. On subsequent pages, averages and
ranges of morphometric data and more-detailed
descriptions of development are presented on a day-by-
day basis.
Within the tables, we have attempted to list
morphometric data in descending order of utility.
Priority is given to characteristics with a fast growth
rate, high ease and accuracy of measuring, and
prominence in the literature. Priority was also given
to those characteristics that proved useful for aging
via field trials, preliminary analysis, and through
prior experience aging altricial nestlings. For
comparative purposes, the variables are listed in the
same order for each day and species.
We recommend a systematic approach when using
the tables for aging nestlings, beginning with an
initial filtering of possible age ranges using the
information on the first page of each species account.
These age ranges can then be further refined
through the use of the daily descriptions.
Measurements and Terminology
It is important that measurements are taken
in a standard format, using terminology that is
consistent. The variables described below were
taken for each species in this guide and are
presented in the account tables. For several of the
measurements used, we followed guidelines as
described by Pyle (1997) or Baldwin et al. (1931).
Measurements taken with electronic calipers are
to the nearest 0.01 mm and measurements taken
with a ruler are to the nearest 0.5 mm. Weight was
measured with an electronic scale to the nearest 0.1
g. A full treatment on the methods used to collect
this data is provided in Appendix B.
Feather definitions:
Apteria: The naked spaces found between the
feather tracts.
Contour feathers: The feathers of the head, body,
and coverts excluding any remiges or rectrices.
Eruption: The breaking down of the pin sheath
usually occurring at the distal tip of the pin,
exposing the feather.
Neossoptiles: Down feathers present when a bird
hatches.
Pterylae: Areas on the skin from which feathers
grow; the feather tracts.
Papillae: A small projection of tissue usually
used to describe feathers at an early stage of
development prior to emergence from the skin.
Methods
Methods
Fig. 1. Dorsal and ventral views of a nestling with the individual feather tracts marked and identified.
6 A Guide to Nestling Development and Aging in Altricial Passerines
Fig. 2. Tarsus with measurement indicators at the
tibiotarsus joint and distal end of the last leg scale.
Remiges: The flight feathers of the wing,
including the primaries, secondaries, and tertials.
Rectrices: The flight feathers of the tail.
Teleoptiles: All flight and contour feathers found
on a bird.
Weight. –– Weight is taken by placing the bird
directly on the scale (older chicks may need to
be placed in a container). To reduce differences,
this should be the last measurement taken so the
nestling can defecate before weight is recorded.
Tarsus.—Tarsus is measured with calipers from the
tibiotarsus joint to the distal end of the last leg scale
before the toes emerge (Fig. 2). When it is difficult
to see the end of the tibiotarsus joint, feel for it with
fingertips; likewise, to find the last leg scale before
the toes emerge, bend the foot and place one end
of the calipers at the bend, checking that the bend
is indeed at the distal end of the last leg scale. It
may help to become familiar with the number of
scales present on the ankle before the toes emerge.
This helps because identifying the last leg scale can
sometimes be difficult, especially in younger birds.
Wing chord.––Early in development, the wing is
measured with a wing ruler from the bend of the
wrist to tip of the distal segment of the forelimb.
Once the primary pins have emerged, wing chord is
measured with a wing ruler, unflattened, from the
bend of the wrist to the tip of the primaries (Fig. 3).
Fig. 3. Wing chord as measured with a wing ruler,
without flattening or pressing down on the wing.
Primary and rectrix pin lengths.––Pin lengths are
measured with a ruler from the point of emergence
from the skin to the end of the feather or pin (Fig. 4).
Fig. 4. Pin lengths as measured from the point of
emergence from the skin.
Culmen.––Culmen is measured with calipers from
the anterior end of the nostrils to the tip of the
bill (Fig. 5). For practical reasons, the culmen in
some species may need to be measured differently.
Exposed culmen is an alternate measurement taken
for some species and is measured along the ridge of
the upper mandible from the tip of the feathers at
the base of the bill to the bill tip. If you are uncertain
about how to measure the bill in a species, you
should consult the literature (Pyle 1997).
Fig. 5. The culmen as measured from nares to tip.
Eyes.––Eyes are described as closed, partially open
when the eyelids begin to open, or fully open when
they appear fully alert and exposed.
Total length.––Total length is a measure of body size
and is taken from the tip of bill to the tip of the tail
bud with the bird placed on its back along a ruler
(Fig. 6). For consistency, the chick should be in a
relaxed and natural position with its body and neck
gently stretched out so that its bill is almost parallel
with the ruler.
Fig. 6. Total length taken from the tip of the bill to
the tail bud.
Longest broken primary.––The longest exposed
primary (exposed feather portion only) is measured
with a ruler from the point of emergence from the
pin shaft to the distal tip of the feather itself (Fig. 7).
Fig. 7. The exposed portion of the longest broken
primary as measured with a ruler.
Gape and rictus.––The gape (mouth opening) is
measured with calipers at its widest length (Fig.
8). The pliable tissue (rictus) at base of the bill
Results 7
should not be bent or squeezed by the calipers
during measurement of the gape. The gape can
grow quickly early in the nestling period and
measurements can increase or decrease greatly
between days as the rictal tissue contracts and
expands. Hence, the gape should be both measured
and used with caution.
Fig. 8. The gape as measured with calipers.
Physical and behavioral descriptors.––Examples
of behavioral data include movement and begging
behavior, opening of eyes, call notes, shivering, and
reaction to the observer. We describe appendage
movement abilities and begging behavior as very
slow and weak, periodic; slow and weak, but steady;
quick and uncontrolled, frequent; or quick and
deliberate. Any sounds, skin or bill color, and notable
changes in appearance are also described.
Species Account Tables
Species information.—Species accounts start with
nest-period information, important to aging nests
found before hatching. Nest-period information
includes means and ranges in clutch size, nest
building time, incubation period, and nestling period.
These parameters may vary temporally and spatially
and are more accurate when calculated from your
specific population (versus from the literature).
Indicator table.––This table provides an “at a
glance” reference to prominent developmental
events and their approximate day of appearance.
Included are events that were found to be reliable
for aging within one or two days and/or were easy to
note visually. This table should be used together with
the feather development table. The daily accounts
can be consulted for more detail.
General feather development.––This table provides
a quick reference to prominent feather development
events and their approximate day of appearance.
The general progression of feather development is
shown to guide users to the approximate age range
of nestlings. A range of possible ages should be
selected using this table together with the indicator
table described above. The daily accounts can then
be consulted for more detail.
Key visual indicators.—List of visual descriptors
we found to be prominent and reliable for each day
that can serve to reinforce age estimates. Examples
of descriptors include behavior, general appearance,
color changes, etc. Typical dates for banding are
noted here as are cautions regarding premature
fledging (“jumping”).
Photographs.––A representative photograph is
presented for each day. These photos can be used
by field biologists to become familiar with the
general appearance of the nestlings, including the
appearance of key visual indicators and feather
tracts.
Feather tract data.––The percentage of individuals
at a given developmental stage for each feather
tract is presented. Feather development events are
indicated respectively as “Not Visible - N”, “Visible -
V” (below skin), “Pin - P” (above and broken through
skin), “Unsheathing - U” (feather partially exposed),
or “Fully Unsheathed - F” for each individual tract
(Fig. 9). The most advanced stage of a given feather
tract is indicated. For example, a tract with exposed
pins of which only a few are unsheathing is marked
as U for unsheathing. Feather tracts are listed in the
same order each day for ease of comparison across
days. Tracts are listed beginning with the capital
tract, then continuing posteriorly and ending with
the ventral tract. The sample size in individuals is
provided for each feather tract.
Pin (above and broken through skin)
Visible (below skin)
Unsheathing (feather partially exposed)
Fig. 9. Example of feather development and
appearance, using a Wrentit on Day 7.
Morphometric data.––Growth data (mean, standard
deviation, and range) are presented for several
measurements to provide indices of body size for
each day. The sample unit is the number of nestlings
measured.
General description.––A more complete description
of the appearance of feather tracts and behavioral
characteristics is given for each day of nestling
development.
8 A Guide to Nestling Development and Aging in Altricial Passerines
Species Accounts
Dusky Flycatcher
Empidonax oberholseri
Data collection: Lassen National Forest, Tehama County, California. Nests: n = 9 (2004)
Nest Period Data: No data
Building: No data
Clutch size: No data
Incubation period: No data
Nestling period: No data
Indicator Table: Dusky Flycatcher visual characteristics typical at a given age.
No pins are visible 1
Alar pins in a band centered across wing 2
Alar pins have grown towards posterior edge of wing 3
Alar pins have grown to the wing edge and may be
pushing out on skin 4
Alar pins have emerged 4-5
Eyes begin to open 5-6
Dorsal and ventral tracts begin to unsheathe 7
All feather tracts begin to unsheathe 8
Primary pins begin to unsheathe 9
Young appear feathered due to extensive unsheathing 10
Contrasting buffy wing bars are readily visible 10-11
Contour feather pins are not visible due to
extensive unsheathing 12
Indicator characteristics Age Indicator characteristics Age
General Feather Development: Dusky Flycatcher feather tract development by day. Most advanced stage
is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or
F-Fully unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N N N N V N N N N
2 N N N N V N N N N V
3 N V N V N V V N V N N V N V
4 V P V P V P V P V P N V V P V P
5 V P P V P V P V P V P V P V P
6 P P U P U P V P V P V P P U
7 P P U P U P U P U P U P U P U
8 U U U U U U U U
9 U U U U U U U U
10 U U U U U U U U
11 U U U U U U U U
12 U U U U U U U U
Results
Results 9
Day 1 Key Visual Indicators:
- No pins are visible
- Down may be matted
- Young are small (egg size)
Feather Tract Development
Tract N V P U F n
Capital 100 12
Dorsal 100 12
Humeral 100 12
Alar 84 16 12
Femoral 100 12
Crural 100 12
Caudal 100 12
Ventral 100 12
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 1.475 ± 0.325 1.0 2.0 12
Tarsus 5.03 ± 0.486 4.5 5.8 12
Wing Chord 5.8 ± 0.411 5.3 6.5 12
Culmen 1.85 ± 0.392 1.4 2.5 12
Outer Primary 0 0 0 12
Outer Rectrix 0 0 0 12
Longest Broken Primary 0 0 0 12
Length 30.58 ± 2.392 28.0 35.0 12
Gape 6.74 ± 1.750 1.8 9.0 12
General Description
Eyes closed. Young are egg size. No pins are visible below
skin. Down may be moist and matted down and is present
on the capital, humeral, dorsal, alar, crural, and ventral
tracts. Bill is orange-yellow.
Dusky Flycatcher (Empidonax oberholseri) continued
Day 2 Key Visual Indicators:
- Subcutaneous alar pins just visible and centered
along dorsal surface of wing
Feather Tract Development
Tract N V P U F n
Capital 100 6
Dorsal 100 6
Humeral 100 6
Alar 33 67 6
Femoral 100 6
Crural 100 6
Caudal 100 6
Ventral 83 17 6
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 1.95 ± 0.243 1.6 2.3 6
Tarsus 6.02 ± 0.585 5.5 7.1 6
Wing Chord 6.73 ± 0.787 5.8 7.8 6
Culmen 1.88 ± 0.214 1.5 2.1 6
Outer Primary 0 0 0 6
Outer Rectrix 0 0 0 6
Longest Broken Primary 0 0 0 6
Length 31.5 ± 1.643 28.0 35.0 6
Gape 7.2 ± 0.642 6.2 7.9 6
General Description
Eyes closed. Alar pins are becoming visible, are
individually distinguishable, and are centered along the
dorsal surface of the wing. Ventral pins may just be
visible. No other pins are visible.
10 A Guide to Nestling Development and Aging in Altricial Passerines
Day 3 Key Visual Indicators:
- Alar pins have grown towards posterior edge of
wing
- All tracts may be visible except for crural tract
- No pins have emerged
Feather Tract Development
Tract N V P U F n
Capital 33 67 12
Dorsal 8 92 12
Humeral 8 92 12
Alar 100 12
Femoral 33 67 12
Crural 100 12
Caudal 33 67 12
Ventral 17 83 12
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 3.14 ± 0.626 2.1 4.1 12
Tarsus 6.28 ± 0.697 5.3 7.8 12
Wing Chord 7.46 ± 1.141 5.6 6.5 12
Culmen 2.21 ± 0.408 1.5 2.5 12
Outer Primary 0 0 0 12
Outer Rectrix 0 0 0 12
Longest Broken Primary 0 0 0 12
Length 35.75 ± 3.86 31.0 43.0 12
Gape 8.55 ± 0.843 6.6 9.5 12
General Description
Eyes closed. Capital tract may be visible as a few gray
flecks. Dorsal tract visible as a light-gray stripe along
the spine. Humeral tract visible as a short gray band.
Alar pins have grown towards the posterior edge of wing.
Femoral tract may appear as a few individual gray flecks.
Crural tract is not visible. Caudal tract may appear as a
thin light-gray band. Ventral tract is visible below skin.
Dusky Flycatcher (Empidonax oberholseri) continued
Day 4 Key Visual Indicators:
- Alar pins have grown to the posterior edge of wing
and may be pushing out on skin
- Young appear dark overall due to darkening and
lengthening of subcutaneous pins
Feather Tract Development
Tract N V P U F n
Capital 62.5 37.5 8
Dorsal 62.5 37.5 8
Humeral 50 50 8
Alar 62.5 37.5 8
Femoral 88 12 8
Crural 37.5 62.5 8
Caudal 88 12 8
Ventral 50 50 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 4.01 ± 0.574 3.2 5.0 10
Tarsus 8.59 ± 1.099 7.1 10.3 10
Wing Chord 9.55 ± 0.927 8.5 11.1 8
Culmen 2.49 ± 0.335 2.0 3.0 10
Outer Primary 0.1 ± 0.316 0 1.0 10
Outer Rectrix 0 0 0 10
Longest Broken Primary 0 0 0 10
Length 39.6 ± 3.098 35.0 44.0 10
Gape 9.24 ± 0.599 8.0 10.0 10
General Description
Eyes closed. Capital, dorsal, and humeral tracts have
darkened and may be pressing up on skin surface. Alar
pins have grown to the wing edge and may be pushing
out on skin. Femoral pins have darkened and lengthened.
Crural tract just becoming visible. Caudal tract is visible
as a thin dark-gray band. Ventral pins may be pressing up
on skin or some may be just emerging.
Results 11
Day 5 Key Visual Indicators:
- Alar pins have typically emerged
- Contour feather tracts beginning to emerge, just
above skin surface
Feather Tract Development
Tract N V P U F n
Capital 25 75 8
Dorsal 12.5 87.5 8
Humeral 25 75 8
Alar 14 86 7
Femoral 25 75 8
Crural 37.5 62.5 8
Caudal 62.5 37.5 8
Ventral 12.5 87.5 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 4.91 ± 0.926 3.5 6.3 8
Tarsus 8.93 ± 0.991 7.4 10.1 8
Wing Chord 10.51 ± 3.064 3.8 13.4 8
Culmen 2.58 ± 0.324 2.1 3.2 8
Outer Primary 0.56 ± 0.678 0 2.0 8
Outer Rectrix 0 0 0 8
Longest Broken Primary 0 0 0 8
Length 43.25 ± 3.732 40.0 50.0 8
Gape 9.9 ± 0.321 9.5 10.6 8
General Description
Some individuals may begin to open their eyes. Bill is
becoming gray at the tip. Capital pins just beginning to
emerge. Dorsal and humeral tracts typically emerging.
Alar primary and secondary pins have emerged. Femoral
and crural tracts have lengthened and tips may be just
out. Caudal tract band has lengthened. Most ventral pins
have emerged.
Dusky Flycatcher (Empidonax oberholseri) continued
Day 6 Key Visual Indicators:
- Eyes typically opening
- All tracts have typically emerged
- Outer primary pins measure about 2mm in length
Feather Tract Development
Tract N V P U F n
Capital 100 12
Dorsal 83 17 12
Humeral 25 75 8
Alar 100 12
Femoral 8 92 12
Crural 27 73 11
Caudal 27 73 11
Ventral 83 17 11
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 6.34 ± 0.981 4.4 8.3 12
Tarsus 11.03 ± 0.945 9.5 12.6 12
Wing Chord 13.15 ± 2.166 8.7 16.3 12
Culmen 2.83 ± 0.391 2.3 3.5 12
Outer Primary 2.13 ± 1.494 0.5 4.0 12
Outer Rectrix 0.13 ± 0.311 0 1.0 12
Longest Broken Primary 0 0 0 12
Length 43.83 ± 2.368 40.0 47.0 12
Gape 10.63 ± 0.502 9.9 11.5 12
General Description
Eyes typically beginning to open. Most capital tract pins
have emerged. Most dorsal pins have emerged and may
show light tips. Alar pins have emerged, including some
coverts. Primaries and secondaries may show light tips.
Several femoral and crural pins have emerged.
12 A Guide to Nestling Development and Aging in Altricial Passerines
Day 7 Key Visual Indicators:
- Dorsal and ventral tracts typically unsheathing
- Some alar tract coverts may be beginning to un-sheathe
Feather Tract Development
Tract N V P U F n
Capital 100 3
Dorsal 33 67 3
Humeral 67 33 3
Alar 67 33 3
Femoral 67 33 3
Crural 67 33 3
Caudal 67 33 3
Ventral 33 67 3
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 8.33 ± 0.635 7.6 8.7 3
Tarsus 12.43 ± 1.00 11.4 13.4 3
Wing Chord 18.67 ± 1.963 16.4 19.8 3
Culmen 2.97 ± 0.115 2.9 3.1 3
Outer Primary 4.33 ± 0.577 4.0 5.0 3
Outer Rectrix 1.0 ± 0.0 1.0 1.0 3
Longest Broken Primary 0 0 0 3
Length 55.33 ± 2.887 50.0 55.0 3
Gape 11.4 ± 0.458 11.0 11.9 3
General Description
Capital tract pins have lengthened and are still typically in
pin. Dorsal pins have lengthened and some are beginning
to unsheathe. All humeral pins have emerged and may
begin to unsheathe. Alar pins have lengthened and
coverts may be unsheathing. Some femoral and crural
tracts may show white tips or have begun to unsheathe.
Rectrices have begun to emerge. Ventral tract is typically
unsheathing. Young grasp uncontrollably. Bill is becoming
a purplish pink with a gray tip.
Dusky Flycatcher (Empidonax oberholseri) continued
Day 8 Key Visual Indicators:
- All contour feather tracts typically unsheathing
- Some secondaries beginning to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 100 4
Dorsal 100 4
Humeral 100 4
Alar 100 4
Femoral 100 4
Crural 100 4
Caudal 100 4
Ventral 100 4
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 8.81 ± 1.143 6.5 10.4 8
Tarsus 13.18 ± 1.051 11.6 14.5 8
Wing Chord 20.18 ± 4.713 10.1 24.0 8
Culmen 3.51 ± 0.372 3.2 4.3 8
Outer Primary 6.5 ± 2.074 4.0 9.0 6
Outer Rectrix 2.17 ± 1.169 1.0 4.0 6
Longest Broken Primary 0.38 ± 0.744 0 2.0 8
Length 51.0 ± 2.878 46.0 55.0 8
Gape 11.6 ± 0.875 10.1 12.8 8
General Description
Capital tract pins have typically begun to unsheathe.
Some secondaries are beginning to unsheathe. Primaries
are showing white tips or just beginning to unsheathe.
Most pins of all contour feathers have begun to unsheathe.
Bill continues to darken and anteriorly gray. Young can
move and grasp constantly.
Results 13
Day 9 Key Visual Indicators:
- Primary tips beginning to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 25 75 8
Dorsal 100 8
Humeral 100 8
Alar 100 8
Femoral 100 8
Crural 25 75 8
Caudal 12.5 87.5 8
Ventral 100 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 9.075 ± 0.918 7.0 9.8 8
Tarsus 14.13 ± 1.412 11.4 16.2 8
Wing Chord 22.8 ± 2.370 19.8 25.8 8
Culmen 3.39 ± 0.426 2.6 3.9 8
Outer Primary 7.5 ± 2.204 4.0 10.0 8
Outer Rectrix 2.88 ± 1.246 1.0 5.0 8
Longest Broken Primary 0.88 ± 1.126 0 3.0 8
Length 53.38 ± 4.069 46.0 60.0 8
Gape 11.38 ± 0.373 11.1 12.0 8
General Description
All feather tracts are clearly unsheathing, although
sheaths may still be prominent on capital and dorsal
tracts. Primary pins are beginning to unsheathe and most
alar feathers are mostly in their sheath. Young are able
to hop around, though are not well coordinated. May give
contact “pip” calls.
Dusky Flycatcher (Empidonax oberholseri) continued
Day 10 Key Visual Indicators:
- Most alar pins have begun to unsheathe
- Young appear soft due to extent of unsheathing
- Young appear alert
Feather Tract Development
Tract N V P U F n
Capital 100 8
Dorsal 100 8
Humeral 100 7
Alar 100 8
Femoral 100 8
Crural 100 8
Caudal 100 8
Ventral 100 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 10.43 ± 1.132 8.3 11.9 8
Tarsus 14.69 ± 0.872 13.3 16.2 8
Wing Chord 28.95 ± 2.432 24.1 32.0 8
Culmen 3.89 ± 0.259 3.5 4.2 8
Outer Primary 12.5 ± 2.507 8.0 15.0 8
Outer Rectrix 5.13 ± 1.356 3.0 7.0 8
Longest Broken Primary 3.5 ± 1.927 1.0 6.0 8
Length 55.75 ± 3.770 50.0 61.0 8
Gape 11.7 ± 0.623 11.0 12.9 8
General Description
All tracts continue to unsheathe and pin sheaths are
mostly hidden by exposed feathers. Several primaries and
secondaries are now unsheathed about 3-4 mm. Bill has
turned about 75% gray. Young are alert and can hop.
14 A Guide to Nestling Development and Aging in Altricial Passerines
Day 11 Key Visual Indicators:
- Contrasting buffy wing bars are visible
- Young are very alert and can hop readily on the
ground
Feather Tract Development
Tract N V P U F n
Capital 100 6
Dorsal 100 6
Humeral 100 6
Alar 100 6
Femoral 100 6
Crural 100 6
Caudal 100 6
Ventral 100 6
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 10.3 ± 0.346 10.0 10.6 4
Tarsus 15.52 ± 1.134 13.5 16.5 6
Wing Chord 31.8 ± 3.295 27.8 35.5 6
Culmen 3.93 ± 0.398 3.4 4.4 6
Outer Primary 14.0 ± 3.033 9.0 17.0 6
Outer Rectrix 6.77 ± 2.002 3.0 9.0 6
Longest Broken Primary 6.67 ± 2.582 3.0 9.0 6
Length 55.5 ± 4.324 50.0 60.0 6
Gape 11.97 ± 0.294 11.6 12.4 6
General Description
All feather tracts continue to unsheathe extensively.
Primaries are unsheathed about 6-7mm. Contrasting
buffy wing bars are clearly visible along the wing coverts.
Bill has darkened almost entirely except for the gape.
Nestlings are prone to “jump” on this day. Use caution.
Dusky Flycatcher (Empidonax oberholseri) continued
Day 12 Key Visual Indicators:
- Contour feather pins are obscured due to extensive
unsheathing
- May appear similar to Day 11
Feather Tract Development
Tract N V P U F n
Capital 100 7
Dorsal 100 7
Humeral 100 7
Alar 100 7
Femoral 100 7
Crural 100 7
Caudal 100 7
Ventral 100 7
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 11.22 ± 1.030 9.2 12.1 6
Tarsus 16.03 ± 0.325 15.5 16.4 7
Wing Chord 37.8 ± 2.204 34.1 40.5 7
Culmen 4.24 ± 0.416 3.5 4.8 7
Outer Primary 17.57 ± 1.134 16.0 19.0 7
Outer Rectrix 11.0 ± 1.155 9.0 12.0 7
Longest Broken Primary 11.0 ± 6.880 1.0 17.0 7
Length 62.29 ± 2.360 59.0 66.0 7
Gape 12.2 ± 0.455 11.7 13.1 7
General Description
Nestlings appear very similar to Day 11. Wing chord and
longest broken primary have substantially increased in
length. Contour feather pins are obscured by unsheathed
feathers. Nestlings should not be handled if they appear
prone to jump from the nest.
Results 15
Species Accounts
Carolina Wren
Thryothorus ludovicianus ludovicianus
Data collection location: Tennessee Valley Authority Reservation, Muscle Shoals, Colbert County, Alabama
Nests: n = 3 (2001), n = 2 (2002), n = 16 (2004)
Nest Period Data (Haggerty and Morton 1995): Average (range), n = number of nests
Building: no data
Clutch size: 4.3 (3 -- 6) eggs, n = 88
Incubation: 14.8 (12 - 16) days, n = 16
Nestling: 12.2 (10 - 16) days, n = 5
Indicator Table: Carolina Wren visual characteristics typical at a given age.
Alar pins in a band centered across wing 1
Down is matted or moist 1
Alar pins stretched towards posterior edge 2
Primaries and secondaries just emerged 3
Pins of humeral, dorsal, and capital tracts
appear ready to emerge 4
Eyes begin to open 4-5
Alar pin tips appear pale, ready to unsheathe 6
Alar pins begin to unsheathe 7
Pins of most tracts appear ready to unsheathe 7
Contour tracts except capital begin to unsheathe 8
All feather tracts clearly unsheathing 9
Indicator characteristics Age Indicator characteristics Age
General Feather Development: Carolina Wren feather tract development by day. Most advanced stage is
indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or
F-Fully unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N N N V V N N N N
2 N V N V N V V P N N N V N V
3 N V N V N V V P N V N V N V N V
4 V V V P P N V N V N V N V
5 V P V P V P P V P V P V P V P
6 V P V P V P P U V P V P V P V P U
7 V P U P U P U P U P U P U P U P U
8 P U P U P U U P U P U P U U
9 P U U U U U U U U
10 U U U U U U U U
16 A Guide to Nestling Development and Aging in Altricial Passerines
Day 1 Key Visual Indicators:
- Subcutaneous alar pins are centered along the dor-sal
wing surface
- Most other feather tracts are not visible below skin
- Down is often matted and moist, young are egg size.
Feather Tract Development
Tract N V P U F n
Capital 100 35
Dorsal 100 36
Humeral 97 3 36
Alar 100 36
Femoral 100 36
Crural 100 35
Caudal 100 36
Ventral 100 36
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 2.24 ± 0.398 1.6 3.25 36
Tarsus 6.69 ± 0.475 5.6 7.9 36
Wing Chord 6.29 ± 0.541 4.4 7.6 36
Culmen 2.05 ± 0.210 1.6 2.4 36
Outer Primary 0 0 0 26
Outer Rectrix 0 0 0 34
Longest Broken Primary 0 0 0 26
Length 35.5 ± 2.302 32.0 40.0 26
Gape 8.34 ± 0.696 7.1 9.8 24
General Description
Eyes closed and lids appear dark. Bill pale, except for
dark tip; rictus cream yellow to spectrum yellow at
corners. Skin is reddish-pink. Grayish-brown down on
capital, humeral and spinal tracts; often matted. Distinct,
dark primary and secondary pin feathers visible below
skin in alar tract; pins still very small and centered across
dorsal surface of wings. No pigmented pins usually
visible below skin in other tracts. Moves limbs and head
very slowly. Soft “pep” calls heard. Often remains in
curled, embryo-like position with head resting on large
protruding abdomen.
Carolina Wren (Thryothorus ludovicianus ludovicianus) continued
Day 2 Key Visual Indicators:
- Alar pins stretched to posterior edge of wing
Feather Tract Development
Tract N V P U F n
Capital 88 12 26
Dorsal 52 48 27
Humeral 52 48 27
Alar 70 30 27
Femoral 100 27
Crural 100 26
Caudal 93 7 27
Ventral 96 4 27
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 3.13 ± 0.417 2.4 4.0 27
Tarsus 7.67 ± 0.444 6.6 8.7 27
Wing Chord 7.12 ± 0.459 6.4 8.4 27
Culmen 2.35 ± 0.197 2.0 2.8 27
Outer Primary 0 0 0 21
Outer Rectrix 0 0 0 26
Longest Broken Primary 0 0 0 21
Length 39.5 ± 2.524 36.0 45.0 20
Gape 9.51 ± 0.485 8.6 10.2 19
General Description
Eyes closed. Humeral and dorsal tracts may have very
small, dark pigmented pins below skin; appear as small
dark dots. Alar pins under skin larger and merge to give
arm, especially hand, a dark color; no flesh-colored stripe
visible along posterior edge of dorsal surface of arm.
Pigmented pins usually not visible under skin in other
tracts. Skin more flesh colored, less reddish than day 1.
Down fluffy, not matted. Slowly lifts head and begs; often
remains in curled up position.
Results 17
Day 3 Key Visual Indicators:
- Primaries and some secondaries emerged
- Longest primary usually <1mm
Feather Tract Development
Tract N V P U F n
Capital 6 97 33
Dorsal 6 94 33
Humeral 3 97 33
Alar 6 97 33
Femoral 76 24 33
Crural 30 70 33
Caudal 21 79 33
Ventral 55 45 33
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 4.70 ± 0.806 3.3 6.7 33
Tarsus 9.16 ± 0.764 7.9 11.0 33
Wing Chord 8.95 ± 0.847 7.8 12.0 33
Culmen 2.66 ± 0.212 2.3 3.0 33
Outer Primary 0.60 ± 0.400 0 2.0 26
Outer Rectrix 0 0 0 31
Longest Broken Primary 0 0 0 27
Length 44.04 ± 3.130 36.0 50.0 26
Gape 10.46 ± 0.638 9.5 12.1 25
General Description
Eyes closed. Pins of alar tract clearly emerged. Pale tissue
bands may be present in ventral tract and femoral tract.
Subcutaneous pigmented pins in femoral tract may be
visible as small flecks. Dark subcutaneous pins clearly
visible in spinal, humeral and capital tracts. Longest
primary pin (P7) usually 1 mm or less. Caudal tract
visible as subcutaneous gray color and emerged hair-like
pin tips may be visible. Crural tract may have very
small pigmented subcutaneous pins. Upper bill brownish.
Movements more frequent and strong.
Carolina Wren (Thryothorus ludovicianus ludovicianus) continued
Day 4 Key Visual Indicators:
- Pins of humeral, dorsal, and capital tracts appear
ready to emerge
- Longest primary usually between 1 - 2mm
- Pigmented pins becoming visible on ventral tract
near chest and axilla
Feather Tract Development
Tract N V P U F n
Capital 100 24
Dorsal 100 25
Humeral 96 4 25
Alar 100 25
Femoral 32 68 25
Crural 8 92 24
Caudal 4 96 25
Ventral 24 76 25
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 6.20 ± 1.119 4.2 9.5 25
Tarsus 10.82 ± 1.063 9.0 13.9 25
Wing Chord 11.32 ± 1.386 8.7 15.8 25
Culmen 3.15 ± 0.257 2.7 3.5 25
Outer Primary 1.84 ± 0.846 1.0 4.0 23
Outer Rectrix 0.02 ± 0.10 0 0.5 25
Longest Broken Primary 0 0 0 23
Length 49.70 ± 3.560 42.0 58.0 23
Gape 11.67 ± 0.658 10.5 13.0 23
General Description
Eyes partially opened. Longest primary measures
between 1 and 2 mm. Dark, subcutaneous pins visible in
chest area of ventral tract. Dark subcutaneous pins in
capital, femoral, caudal and crural tracts. Subcutaneous
pins of spinal and humeral tracts appear ready to emerge
through skin. Can move body with kicks and wing flaps.
18 A Guide to Nestling Development and Aging in Altricial Passerines
Day 5 Key Visual Indicators:
- Pins on most tracts just emerged or appear ready to
emerge
- All alar pins including coverts have emerged
- Eyes typically appear partially to fully open
Feather Tract Development
Tract N V P U F n
Capital 88 12 33
Dorsal 60 40 33
Humeral 55 45 33
Alar 100 33
Femoral 79 18 3 33
Crural 67 33 33
Caudal 70 30 33
Ventral 79 21 33
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 8.20 ± 1.158 5.9 11.1 33
Tarsus 13.03 ± 0.967 11.4 16.2 33
Wing Chord 15.25 ± 1.860 11.2 20.5 33
Culmen 3.67 ± 0.347 3.0 4.4 33
Outer Primary 4.14 ± 1.757 0 9.0 26
Outer Rectrix 0.10 ± 0.201 0 0.5 31
Longest Broken Primary 0.02 ± 0.096 0 0.5 27
Length 53.19 ± 4.350 43.0 65.0 27
Gape 12.36 ± 0.646 11.2 14.4 25
General Description
Eyes open. Ventral, dorsal, femoral, humeral, crural and
caudal tracts have emerged pins or pins that appear ready
to emerge. Capital pins may emerge in nape region. Bill
and skin of face dark, contrasts with yellow rictus. Can
move body with kicks and wing flaps.
Carolina Wren (Thryothorus ludovicianus ludovicianus) continued
Day 6 Key Visual Indicators:
- Pins on all tracts have emerged
- Tips of primary pins are pale, appear ready to
unsheathe
Feather Tract Development
Tract N V P U F n
Capital 33 67 24
Dorsal 16 84 25
Humeral 8 92 25
Alar 92 8 25
Femoral 24 76 25
Crural 29 71 24
Caudal 16 84 25
Ventral 20 72 8 25
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 9.98 ± 1.484 6.4 13.1 25
Tarsus 15.11 ± 1.021 13.0 18.0 25
Wing Chord 19.18 ± 2.483 14.7 25.6 25
Culmen 4.08 ± 0.437 3.1 4.9 25
Outer Primary 7.64 ± 2.097 4.5 13.0 22
Outer Rectrix 0.33 ± 0.396 0 1.2 24
Longest Broken Primary 0.05 ± 0.147 0 0.5 22
Length 58.13 ± 4.703 47.0 66.0 23
Gape 12.66 ± 0.516 11.6 13.7 23
General Description
Eyes open. Pins usually emerged in all tracts. Begs
directly at nest entrance. May cower and snap bill
(inaudible) when nest is disturbed. Kicks and flaps quickly
and can easily turn itself over when placed on back. Tips of
alar pins pale and look ready to unsheathe. Face dark and
contrasts sharply with yellow rictus.
Results 19
Day 7 Key Visual Indicators:
- Alar pins beginning to unsheathe
- Pins of most tracts have pale tips and appear ready
to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 3 94 3 29
Dorsal 80 20 30
Humeral 83 17 30
Alar 50 50 30
Femoral 77 23 30
Crural 90 10 29
Caudal 90 10 30
Ventral 70 30 30
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 11.90 ± 1.557 7.3 14.9 30
Tarsus 17.07 ± 0.974 13.9 18.6 30
Wing Chord 24.04 ± 2.440 17.5 28.4 30
Culmen 4.46 ± 0.369 3.6 5.2 30
Outer Primary 11.53 ± 2.337 8.0 17.0 20
Outer Rectrix 1.15 ± 0.847 0 4.0 28
Longest Broken Primary 0.38 ± 0.705 0 3.0 20
Length 63.45 ± 4.751 55.0 73.0 20
Gape 12.84 ± 0.661 11.8 14.6 20
General Description
Alar pin tips pale and often unsheathing. Ventral, dorsal,
humeral, and femoral tracts have pins that look ready to
open and unsheathing may begin. Can hold head up off
clipboard. Pins of ventral and femoral tracts cinnamon
colored.
Carolina Wren (Thryothorus ludovicianus ludovicianus) continued
Day 8 Key Visual Indicators:
- All feather tracts typically unsheathing except
capital and caudal
- Appears alert and active
Feather Tract Development
Tract N V P U F n
Capital 78 22 23
Dorsal 21 79 24
Humeral 21 79 24
Alar 100 24
Femoral 4 96 24
Crural 48 52 23
Caudal 71 29 24
Ventral 100 24
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 13.53 ± 1.726 8.4 16.15 24
Tarsus 18.55 ± 1.062 16.0 20.7 24
Wing Chord 28.18 ± 2.645 19.6 33.2 24
Culmen 4.92 ± 0.395 4.2 5.9 24
Outer Primary 14.17 ± 4.222 1.3 21.0 20
Outer Rectrix 2.23 ± 1.280 0 6.0 23
Longest Broken Primary 2.08 ± 1.315 0.5 6.0 19
Length 66.80 ± 6.978 53.0 80.0 20
Gape 13.03 ± 0.608 12.0 14.0 20
General Description
All tracts but capital and caudal have pins that are
clearly ruptured. Very alert; flaps and kicks vigorously,
and usually will not remain still during handling. Eyes
typically stay open during handling. Eyes and face black.
May give fledgling “chip” locator call. Young are typically
ready for banding.
20 A Guide to Nestling Development and Aging in Altricial Passerines
Day 9 Key Visual Indicators:
- All feather tracts clearly unsheathed
- Light brown feathers of ventral tract form two
broad stripes
- Rust colored dorsal feathers form strip on back
Feather Tract Development
Tract N V P U F n
Capital 9 91 22
Dorsal 100 23
Humeral 100 23
Alar 100 23
Femoral 100 23
Crural 5 95 22
Caudal 4 96 23
Ventral 100 23
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 14.85 ± 1.437 10.4 16.5 23
Tarsus 19.77 ± 0.888 18.0 21.5 23
Wing Chord 32.93 ± 1.779 28.5 36.4 23
Culmen 5.16 ± 0.455 4.2 6.0 23
Outer Primary 19.35 ± 2.731 14.0 22.2 15
Outer Rectrix 3.85 ± 0.918 2.0 6.0 21
Longest Broken Primary 5.27 ± 1.280 3.0 8.0 15
Length 71.53 ± 5.805 60.0 83.0 15
Gape 12.75 ± 0.507 12.0 13.5 15
General Description
All tracts have pins that are clearly unsheathed. Upper
wing covert pins clearly unsheathed. Unsheathed feathers
of ventral tract cinnamon colored and form two broad
strips. Unsheathed feathers of dorsal tract form rust
colored strip on back. Very alert; flaps and kicks quickly,
and nestling usually will not remain still. Turns neck and
head to look around. May give fledgling “chip” locator call.
Young are prone to “jump” after this day. Use caution.
Carolina Wren (Thryothorus ludovicianus ludovicianus) continued
Results 21
Species Accounts
Wrentit
Chamea fasciata rufula
Data collection: Point Reyes National Seashore, Marin Co., California. Nests: n = 2 (2003), n = 2 (2004),
n = 7 (2005)
Nest Period Data: Average (range), n = number of nests
Building: 6-7 (3 - 14) days (Geupel and Ballard, 2002)
Clutch size: 3.6 (1 - 5) eggs, n = 733
Incubation: 14.9 (11 - 18) days, n = 192
Nestling: 14.6 (11 - 19) days, n = 242
Indicator Table: Wrentit visual characteristics typical at a given age.
Alar pins centered on dorsal wing surface 1
Alar pins stretched towards posterior edge of wing 2
Crural tract just becoming visible 3
Alar pins have extended to the wing edge 3
Primary and secondary pins appear ready to emerge 4
Capital, dorsal, and humeral tracts just emerged 6
Eyes begin to open 6-7
Alar pin tips are pale, ready to unsheathe 8
Alar pins begin to unsheathe 9
Young appear soft due to extent of unsheathing 10
Indicator characteristics Age Indicator characteristics Age
General Feather Development: Wrentit feather tract development by day. Most advanced stage is indicated
as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully
unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N V N V V N V N N V N
2 N V V V V V N N V N V
3 V V V V V N V V V
4 V V V V P V V V V
5 V V P V P V P V V V V P
6 V P V P U V P U P V P U V V P V P U
7 P P U P U P U V P U V P U V P U P U
8 U U U P U U V P U P U P U
9 U U U U U P U U U
10 U U U U U U U U
11 U U U U U U U U
22 A Guide to Nestling Development and Aging in Altricial Passerines
Day 1 Key Visual Indicators:
- Skin appears uniformly fleshy pink except around
eyes
- Capital tract pins are not visible
- Alar pins are centered along dorsal wing surface
Feather Tract Development
Tract N V P U F n
Capital 100 6
Dorsal 100 6
Humeral 50 50 6
Alar 100 6
Femoral 83 17 6
Crural 100 6
Caudal 50 50 6
Ventral 100 6
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 1.78 ± 0.248 1.6 2.1 6
Tarsus 6.27 ± 1.310 4.58 7.2 6
Wing Chord 4.31 ± 0.696 3.5 5.17 6
Culmen 1.93 ± 0.305 1.6 2.27 4
Outer Primary 0 0 0 6
Outer Rectrix 0 0 0 6
Longest Broken Primary 0 0 0 5
Length 32.5 ± 1.291 31.0 34.0 4
Gape 7.32 ± 0.282 7.08 7.7 4
General Description
Eyes and ears closed. Ears visible as indentations. Bill
is ocher with orange yellow, with an ashy olive tip, and
a sulfur yellow gape. The nares are just barely visible.
A very small white egg tooth is visible. Skin color is
uniformly fleshy pink throughout head and body except
for around the eyes, which are blackish gray. Head and
body are completely naked. Capital, dorsal, humeral,
and caudal tracts are visible as very light gray areas
formed by faintly pigmented pins. Femoral and ventral
tracts not visible. Flight feather pins on the wings are
distinguishable as individual pins and are centered on
the wing as a gray band. Limbs are moved around slowly.
Young are struggling to lift head up.
Wrentit (Chamea fasciata rufula) continued
Day 2 Key Visual Indicators:
- Back of head beginning to darken as capital tract
pins begin to darken
- Dorsal tract area beginning to darken forming a
light gray stripe
- Alar pins stretched towards posterior edge of wing
Feather Tract Development
Tract N V P U F n
Capital 27 73 11
Dorsal 100 11
Humeral 100 11
Alar 100 11
Femoral 100 11
Crural 100 11
Caudal 18 82 11
Ventral 55 45 11
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 2.43 ± 0.548 1.7 3.4 9
Tarsus 7.69 ± 1.024 6.02 9.13 11
Wing Chord 5.0 ± 0.597 4.0 6.03 11
Culmen 2.22 ± 0.277 1.93 2.67 9
Outer Primary 0 0 0 11
Outer Rectrix 0 0 0 11
Longest Broken Primary 0 0 0 11
Length 33.8 ± 2.348 29.0 36.0 10
Gape 8.02 ± 0.605 6.87 8.94 10
General Description
Eyes and ears closed. Nares visible as a short notch. Egg
tooth may still be present, though not as prominent as
day 1. Skin is fleshy pink except for the area around eyes,
top of head, and dorsal tract areas, which are blackish
gray and wrinkled. Capital tract pins visible as light spots.
Femoral tract is just visible as spotting. Dorsal tract is
visible as a blackish gray stripe (1-2 mm wide). Ventral
tract visible as gray spotting down the throat and sides
of chest, becoming flesh colored along belly. Alar pins are
individually distinguishable and are stretched towards
the posterior edge of the wing. Humeral tract is visible
as spotting forming a light gray band. Crural tract is not
visible. Caudal tract is just visible. Young are able to move
limbs quickly; are uncoordinated.
Results 23
Day 3 Key Visual Indicators:
- Alar pins have grown to the posterior edge of wing
and press up on dorsal wing surface
- Crural tract just becoming visible as gray flecks
Feather Tract Development
Tract N V P U F n
Capital 100 13
Dorsal 100 13
Humeral 100 13
Alar 100 13
Femoral 100 13
Crural 38 62 13
Caudal 100 13
Ventral 100 13
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 3.51 ± 0.668 2.4 4.5 13
Tarsus 9.17 ± 0.937 7.64 10.73 13
Wing Chord 5.54 ± 0.520 5.0 6.51 13
Culmen 2.52 ± 0.229 2.16 2.88 12
Outer Primary 0 0 0 13
Outer Rectrix 0 0 0 13
Longest Broken Primary 0 0 0 12
Length 38.08 ± 2.275 34.0 42.0 12
Gape 9.16 ± 0.688 8.25 9.94 12
General Description
Eyes closed. Ears closed. Remnant of egg tooth still may
be visible. Skin a darker more purple fleshy pink. Skin
around head is dark gray with much wrinkling. Capital
tract is visible as gray flecks. Humeral tract is visible as
a dark stripe about 5 mm in length. Dorsal tract is visible
as a dark gray stripe with a separate darkened area near
base of tail bud. Alar pins have extended to the edge of
the wing and are pressing up on the dorsal surface of the
wing. Femoral tract is visible as dark gray flecks in 2-3
short rows. Crural tract is just visible as a few gray flecks.
Ventral tract is visible as gray flecks down the throat and
sides of chest.
Wrentit (Chamea fasciata rufula) continued
Day 4 Key Visual Indicators:
- Primary and secondary pins appear ready to
emerge
Feather Tract Development
Tract N V P U F n
Capital 100 12
Dorsal 100 12
Humeral 100 12
Alar 92 8 12
Femoral 100 12
Crural 100 12
Caudal 100 12
Ventral 100 12
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 4.42 ± 0.804 3.4 6.2 12
Tarsus 10.60 ± 1.406 8.01 13.02 12
Wing Chord 6.96 ± 1.573 5.5 10.0 12
Culmen 2.55 ± 0.230 2.05 2.8 12
Outer Primary 0.08 ± 0.289 0 1.0 12
Outer Rectrix 0 0 0 12
Longest Broken Primary 0 0 0 12
Length 42.0 ± 2.697 39.0 47.0 12
Gape 9.80 ± 0.824 8.61 11.1 12
General Description
Eyes and ears closed. Nestlings are mostly naked. Capital
tract is visible as flecks covering the head. Humeral and
femoral tracts are visible as short dark gray stripes.
Primary and secondary pins appear ready to emerge.
Some body pins are pressing out against skin. Dorsal
tract appears as a solid dark gray wrinkled stripe. Crural
tract is visible as gray flecks. Individual caudal pins
are distinguishable. Small hair-like projections appear
where the rectrices will protrude. Ventral tract appears
as a darker, more pronounced stripe composed of gray
pins anteriorly and flesh colored pins posteriorly. Young
sporadically lift body and head by kicking with their legs
and flapping wings.
24 A Guide to Nestling Development and Aging in Altricial Passerines
Day 5 Key Visual Indicators:
- Capital, dorsal, humeral, and femoral tracts pushing
up on skin surface, appear ready to emerge
- Alar pins typically just emerged
Feather Tract Development
Tract N V P U F n
Capital 100 10
Dorsal 90 10 10
Humeral 80 20 10
Alar 40 60 10
Femoral 100 10
Crural 100 10
Caudal 100 10
Ventral 90 10 10
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 5.61 ± 0.522 5.1 6.9 10
Tarsus 12.41 ± 1.664 9.56 15.15 10
Wing Chord 9.7 ± 2.275 6.0 13.0 10
Culmen 3.06 ± 0.162 2.84 3.3 8
Outer Primary 0.35 ± 0.242 0 0.5 10
Outer Rectrix 0 0 0 9
Longest Broken Primary 0 0 0 8
Length 43.75 ± 2.550 40.0 46.0 8
Gape 10.60 ± 0.362 10.17 11.03 8
General Description
Eyes closed. Ear canals may begin to open. Nestlings are
mostly naked with most feather tract pins now pushing
up on the skin surface. Dark bill tip color now extends to
all other parts of the bill except for the rictus and nares.
The rictus is turning a deeper yellow and the area around
the nares is an olive buff yellow. Capital tract pins have
begun to push up on the skin. Anterior humeral pins and
some ventral pins may have just emerged. Some or all
primaries and secondaries typically emerging.
Wrentit (Chamea fasciata rufula) continued
Day 6 Key Visual Indicators:
- Capital, dorsal, and humeral tracts just emerged
- Eyes typically begin to open
- Outer primary measures 1-2mm
Feather Tract Development
Tract N V P U F n
Capital 43 57 14
Dorsal 14 64 22 14
Humeral 14 72 14 14
Alar 100 14
Femoral 50 36 14 14
Crural 100 14
Caudal 71 29 14
Ventral 29 57 14 14
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 6.96 ± 0.592 5.7 8.0 14
Tarsus 14.44 ± 1.715 11.66 17.79 14
Wing Chord 12.61 ± 3.420 6.0 19.5 14
Culmen 3.13 ± 0.268 2.53 3.53 12
Outer Primary 1.35 ± 0.798 0 30.0 13
Outer Rectrix 0 0 0 13
Longest Broken Primary 0 0 0 12
Length 47.27 ± 2.149 45.0 51.0 11
Gape 10.98 ± 0.484 10.24 11.99 12
General Description
Eyes may begin to partially open. Ear canals appear
open. Nestlings appear “spiky”, with many pins now just
out above the skin surface. The area around the nares is
turning ash olive in color. Most primary and secondary
pins have emerged. 9th primary measures 1-2 mm. Some
wing covert pins may have emerged. Ventral pins may
be just out with the exception of those anterior to the
furculum. Crural tract pins have not emerged. Caudal
tract typically not emerged.
Results 25
Day 7 Key Visual Indicators:
- Dorsal, humeral, femoral, and ventral tracts begin to
unsheathe
- Caudal pins have emerged
- Eyes typically partially open
Feather Tract Development
Tract N V P U F n
Capital 85 15 13
Dorsal 69 31 13
Humeral 38 62 13
Alar 85 15 13
Femoral 8 38 54 13
Crural 70 15 15 13
Caudal 15 77 8 13
Ventral 38 62 13
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 7.74 ± 0.900 6.8 10.0 14
Tarsus 16.16 ± 1.430 14.15 18.7 14
Wing Chord 14.76 ± 2.793 9.0 20.0 14
Culmen 3.44 ± 0.195 3.17 3.79 12
Outer Primary 2.75 ± 1.141 1.0 5.0 14
Outer Rectrix 0.32 ± 0.249 0 0.5 14
Longest Broken Primary 0.04 ± 0.144 0 0.5 12
Length 48.42 ± 2.999 44.0 54.0 12
Gape 11.15 ± 0.513 10.23 12.23 12
General Description
Eyes are partially open. Bill continues to darken. Dorsal,
humeral, femoral, and ventral tracts begin to unsheathe.
Most pins of the remiges have clearly emerged. P9
measures about 5 mm.
Wrentit (Chamea fasciata rufula) continued
Day 8 Key Visual Indicators:
- Most feather tracts typically just unsheathing
except for crural and caudal tract
Feather Tract Development
Tract N V P U F n
Capital 37.5 62.5 8
Dorsal 100 8
Humeral 100 8
Alar 12.5 87.5 8
Femoral 100 8
Crural 75 25 8
Caudal 62.5 37.5 8
Ventral 12.5 87.5 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 8.75 ± 0.327 8.4 9.2 6
Tarsus 17.25 ± 1.032 15.31 18.38 8
Wing Chord 18.2 ± 1.010 17.0 20.0 8
Culmen 3.68 ± 0.200 3.38 3.97 6
Outer Primary 4.29 ± 0.907 3.0 5.18 8
Outer Rectrix 0.63 ± 0.231 0.5 1.0 8
Longest Broken Primary 0 0 0 6
Length 50.67 ± 1.033 49.0 52.0 6
Gape 11.2 ± 0.451 10.61 11.81 6
General Description
Eyes are partially open. Bill continues to darken.
All tracts except crural and caudal are now typically
beginning to unsheathe. Remiges have lengthened, and
their tips may appear white and ready to unsheathe.
P9 measures about 7 mm. Some wing coverts and
secondaries may be unsheathing. Movement is constant
but uncoordinated.
26 A Guide to Nestling Development and Aging in Altricial Passerines
Day 9 Key Visual Indicators:
- Primary tips appear pale and ready to unsheathe
or begin to unsheathe
- All feather tracts are unsheathing
- Secondary pins begin to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 100 10
Dorsal 100 10
Humeral 100 10
Alar 100 10
Femoral 100 10
Crural 20 80 10
Caudal 100 10
Ventral 100 10
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 9.85 ± 0.463 9.1 10.5 11
Tarsus 19.37 ± 1.696 16.97 22.73 12
Wing Chord 22.08 ± 2.712 19.0 28.0 12
Culmen 3.87 ± 0.428 3.29 4.55 10
Outer Primary 7.74 ± 1.402 6.0 10.0 12
Outer Rectrix 1.81 ± 1.269 0.5 5.0 12
Longest Broken Primary 1.5 ± 0.972 0 3.0 10
Length 52.6 ± 2.633 49.0 57.0 10
Gape 11.25 ± 0.485 10.49 11.79 10
General Description
Eyes are open most of the time. Nestlings beginning
to appear soft due to the extent of the unsheathed pin
feathers. Bill darkening may begin to extend into the
gape. All body pins continue to unsheathe. Primaries and
secondaries may begin to unsheathe. P9 measures about
10 mm.
Wrentit (Chamea fasciata rufula) continued
Day 10 Key Visual Indicators:
- Capital, dorsal, and ventral tracts appear feathered
due to the extent of exposed feathers
- Young appear alert, though movement is not well
coordinated
- Primary pins unsheathing
Feather Tract Development
Tract N V P U F n
Capital 100 6
Dorsal 100 6
Humeral 100 6
Alar 100 6
Femoral 100 6
Crural 100 6
Caudal 100 6
Ventral 100 6
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 10.7 ± 0.544 10.0 11.4 6
Tarsus 20.50 ± 1.325 19.11 21.98 6
Wing Chord 24.67 ± 1.633 23.0 27.0 6
Culmen 3.93 ± 0.214 3.72 4.15 4
Outer Primary 8.44 ± 1.512 6.0 10.52 6
Outer Rectrix 2.85 ± 0.943 2.0 4.0 6
Longest Broken Primary 2.75 ± 0.957 2.0 4.0 4
Length 54.0 ± 1.826 52.0 56.0 4
Gape 10.96 ± 0.386 10.4 11.29 4
General Description
Eyes are open most of the time. Nestlings appear
feathered with apteria mostly covered along back and
flanks. Most alar pins are unsheathing. Body pins continue
to unsheathe. P9 measures about 12 mm. Unsheathed
portion of rectrices about 2 mm. Young are typically ready
for banding.
Results 27
Species Accounts
Sprague’s Pipit
Anthus spragueii
Data collection: Bowdoin National Wildlife Refuge, Phillips County, Montana. Nests: n = 1 (2004).
Nest Period Data: Average (range). n = number of nests
Building: No data
Clutch size: 4.6 (1 - 6) eggs, n = 123
Incubation: 12.2 (7 - 15) days, n = 85
Nestling: 13.1 (9 - 17) days, n = 17
Indicator Table: Sprague’s Pipit visual characteristics typical at a given age.
No feather tracts visible below skin 1
Feather tracts may be just visible as stippling
on skin or small dark spots 2
No data 3
Eyes partially open. Alar tracts beginning to emerge 4
Eyes appear fully open. Pin feathers are out on some
tracts 5
Pin feathers emerged on all tracts 6
Some tracts begin to unsheathe 7
All tracts begin to unsheathe. Primaries begin to
unsheathe 8
No data 9
Primaries are unsheathed about 1 mm 10
Sheathes on most feather tracts no longer visible or
obscured by feathers 11
Indicator characteristics Age Indicator characteristics Age
General Feather Development: Sprague’s Pipit feather tract development by day. Most advanced stage is
indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or
F-Fully unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N N N N N N N N
2 V V V V N N V
3
4 V V V P V V V V
5 V P P P P V V P
6 P P P P P P P P
7 P U U P U P P U
8 U U U U U U U U
9
10 U U U U U U U U
11 U U U U U U U U
12 U U U U U U U U
28 A Guide to Nestling Development and Aging in Altricial Passerines
Sprague’s Pipit (Anthus spragueii) continued
Day 1 Key Visual Indicators:
- No feather tracts visible beneath skin
- Eyes closed
- Nestling may be curled into a ball
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 2.5 2.2 2.8 2
Tarsus 6.59 6.00 7.19 2
Wing Chord 6.0 6.0 6.0 2
Culmen 2.17 2.08 2.27 2
Outer Primary 0 0 0 2
Outer Rectrix 0 0 0 2
Longest Broken Primary 0 0 0 2
Length 37.5 37.0 38.0 2
Gape 7.86 7.78 7.95 2
General Description
Skin and legs salmon colored. Long, light grey (almost
white) down on most feather tracts but no tracts are
visible beneath skin. Rictus yellow. Eyes closed. May
display weak or shaky gaping. Can’t hold head up. Lays
flat on belly or may curl into ball shape. Quiet.
Day 2 Key Visual Indicators:
- Eyes closed
- Most feather tracts (except caudal and crural)
becoming visible as stippling on skin or very
small dark spots
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 3.3 3.3 3.4 2
Tarsus 7.81 7.76 7.86 2
Wing Chord 7.0 7.0 7.0 2
Culmen 2.39 2.32 2.46 2
Outer Primary 0 0 0 2
Outer Rectrix 0 0 0 2
Longest Broken Primary 0 0 0 2
Length 40.5 40.0 41.0 2
Gape 9.08 8.88 9.29 2
General Description
Appearance very much the same as Day 1. Most feather
tracts (except caudal and crural) becoming visible as small
dark spots under skin or stippling on skin surface. Eyes
closed. More movement than Day 1 but still weak and
shaky. Quiet.
Results 29
Day 3 No data
Sprague’s Pipit (Anthus spragueii) continued
Day 4 Key Visual Indicators:
- Eyes partially open
- All feather tracts visible with alar just beginning to
emerge
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 6.7 6.6 6.8 2
Tarsus 11.38 10.97 11.80 2
Wing Chord 11.0 10.0 12.0 2
Culmen 3.27 3.16 3.38 2
Outer Primary 0 0 0 2
Outer Rectrix 0 0 0 2
Longest Broken Primary 0 0 0 2
Length 48.5 48.0 49.0 2
Gape 11.38 10.94 11.82 2
General Description
Skin, legs and bill pink. Rictus yellow. Still downy.
All tracts visible under skin. Alar tract just beginning
to emerge. Eyes may be partially open. Movement is
stronger but not held for long. One nestling made soft
clicking noises.
30 A Guide to Nestling Development and Aging in Altricial Passerines
Day 5 Key Visual Indicators:
- Eyes fully open
- Pin feathers on wings and most body tracts
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 50 50 2
Crural 100 2
Caudal 100 2
Ventral 50 50 2
Morphometric Data
Measurements Mean Min Max n
Weight 8.0 7.8 8.3 2
Tarsus 13.47 13.18 13.76 2
Wing Chord 12.0 11.0 13.0 2
Culmen 3.50 3.49 3.52 2
Outer Primary 1.0 1.0 1.0 2
Outer Rectrix 0 0 0 2
Longest Broken Primary 0 0 0 2
Length 50.5 50.0 51.0 2
Gape 12.23 12.11 12.35 2
General Description
Eyes fully open. Pins emerging on dorsal, alar and
humeral tracts and may be emerging on ventral and
femoral. Not much movement, some gaping. Quiet.
Sprague’s Pipit (Anthus spragueii) continued
Day 6 Key Visual Indicators:
- Pin feathers have emerged on all tracts
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 11.7 11.2 12.2 2
Tarsus 15.75 15.33 16.17 2
Wing Chord 17.0 16.0 18.0 2
Culmen 3.92 3.88 3.97 2
Outer Primary 3.5 3.0 4.0 2
Outer Rectrix 0.5 0 1.0 2
Longest Broken Primary 0 0 0 2
Length 53.0 51.0 55.0 2
Gape 12.79 12.77 12.81 2
General Description
Down on dorsal, capital and alar tracts. Down is approx.
10 mm long but getting more sparse. Pin feathers have
emerged on all tracts, however caudal may be barely
emerging. May balance on rump and tarsus. Soft clicking
noises.
Results 31
Day 7 Key Visual Indicators:
- Some feathers beginning to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 50 50 2
Alar 100 2
Femoral 50 50 2
Crural 100 2
Caudal 100 2
Ventral 50 50 2
Morphometric Data
Measurements Mean Min Max n
Weight 13.4 12.9 14.0 2
Tarsus 18.13 17.90 18.36 2
Wing Chord 21.0 20.0 22.0 2
Culmen 4.35 4.14 4.57 2
Outer Primary 6.5 6.0 7.0 2
Outer Rectrix 1.5 1.0 2.0 2
Longest Broken Primary 0 0 0 2
Length 58.0 56.0 60.0 2
Gape 13.44 13.24 13.64 2
General Description
Sparse down on dorsal, capital and alar tracts. Dorsal pins
unsheathing and possibly ventral, femoral and humeral.
More alert. Makes soft clicking noises and occasionally a
soft chirp.
Sprague’s Pipit (Anthus spragueii) continued
Day 8 Key Visual Indicators:
- All tracts unsheathing
- Primaries beginning to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 15.0 13.9 16.1 2
Tarsus 19.79 19.71 19.88 2
Wing Chord 27.0 26.0 28.0 2
Culmen 4.54 4.47 4.62 2
Outer Primary 10.0 9.0 11.0 2
Outer Rectrix 3.5 3.0 4.0 2
Longest Broken Primary 0 0 0 2
Length 62.5 62.0 63.0 2
Gape 13.71 13.69 13.73 2
General Description
Down same as Day 7. All feather tracts unsheathing.
Primaries just beginning to unsheathe. May make soft
clicking noises.
32 A Guide to Nestling Development and Aging in Altricial Passerines
Day 9 No data
Sprague’s Pipit (Anthus spragueii) continued
Day 10 Key Visual Indicators:
- Primary pins unsheathing about 1 mm
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 19.3 18.4 20.3 2
Tarsus 21.98 21.72 22.24 2
Wing Chord 36.5 34.0 39.0 2
Culmen 5.09 4.93 5.26 2
Outer Primary 17.0 15.0 19.0 2
Outer Rectrix 7.5 7.0 8.0 2
Longest Broken Primary 3.5 1.0 6.0 2
Length 76.0 75.0 77.0 2
Gape 13.86 13.76 13.96 2
General Description
Down still apparent on head and back and a little on the
wings. Most feathers well out of sheaths except around the
face. Primaries have emerged. Feathers on head and back
dark, chest is brown and belly is tan/white. Much more
active with some soft clicking and chirping.
Results 33
Sprague’s Pipit (Anthus spragueii) continued
Day 12 Key Visual Indicators:
- Appearance similar to Day 11
- Base of remiges in sheath, but obscured by exposed
feathers
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 19.0 18.1 20.0 2
Tarsus 22.82 22.57 23.08 2
Wing Chord 45.5 43.0 48.0 2
Culmen 5.61 5.33 5.89 2
Outer Primary 24.0 22.0 26.0 2
Outer Rectrix 10.5 10.0 11.0 2
Longest Broken Primary 13.0 12.0 14.0 2
Length
Gape 13.24 13.12 13.36 2
General Description
Down very sparse on back and head, almost gone from
the wings. Base of remiges still in sheath, but obscured
by exposed feathers. Very active, standing and jumping.
Some chirping/squawking noises mostly while trying to
escape.
Day 11 Key Visual Indicators:
- Sheaths on most feather tracts are no longer visible
except on wings
Feather Tract Development
Tract N V P U F n
Capital 100 2
Dorsal 100 2
Humeral 100 2
Alar 100 2
Femoral 100 2
Crural 100 2
Caudal 100 2
Ventral 100 2
Morphometric Data
Measurements Mean Min Max n
Weight 18.8 18.3 19.4 2
Tarsus 22.4 22.3 22.5 2
Wing Chord 41.0 38.0 44.0 2
Culmen 5.22 5.18 5.27 2
Outer Primary 22.0 20.0 24.0 2
Outer Rectrix 9.5 9.0 10.0 2
Longest Broken Primary 6.0 3.0 9.0 2
Length 78.0 77.0 79.0 2
Gape 13.42 13.29 13.55 2
General Description
Still some sparse down. Sheaths at bottom of all feathers
but only visible on wings. Very active but quiet.
34 A Guide to Nestling Development and Aging in Altricial Passerines
Species Accounts
Song Sparrow
Melospiza melodia gouldii
Data collection: Point Reyes National Seashore, Marin County, California. Nests: n = 11 (2004), n = 9
(2005).
Nest Period Data: Average (range), n = number of nests
Building: No data
Clutch size: 3 (2 - 5) eggs, n =198
Incubation period: 13 (12 - 16) days, n = 40
Nestling period: 9 (8 - 12) days, n = 55
Indicator Table: Song Sparrow visual characteristics typical at a given age.
Alar pins in a band centered across wing 1
Alar pins have grown towards posterior edge of wing 2
Ventral tract appears as spots from furculum to mid chest 2
Some primary pins are just out 3
All primary and secondary pins are out 3-4
Outer primaries about 2mm long 4
Eyes just beginning to open 5
Some contour pins begin to unsheathe 5
Eyes appear fully open 5-6
Primary pins beginning to unsheathe 7
All feather tracts are unsheathing 7-8
Indicator characteristics Age Indicator characteristics Age
General Feather Development: Song Sparrow feather tract development by day. Most advanced stage is
indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or
F-Fully unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N V N V N V V N V N V N N V
2 N V V N V V P N V N V N V N V
3 V V P V P V P V P N V N V V P
4 V P V P V P P V P V P V P V P
5 V P P U P P V P V P V P V P U
6 V P P U P U P U V P U V P U V P P U
7 P U P U P U P U P U P U V P U P U
8 U U U U U U P U U
Results 35
Day 1 Key Visual Indicators:
- Alar pins centered across wing and not individually
distinguishable
- Young are small (egg size)
- Down may appear moist
- Egg tooth is prominent/visible
Feather Tract Development
Tract N V P U F n
Capital 60 40 20
Dorsal 5 95 20
Humeral 15 85 20
Alar 100 20
Femoral 80 20 20
Crural 95 5 20
Caudal 100 20
Ventral 70 30 20
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 2.28 ± 0.549 1.5 3.8 20
Tarsus 7.02 ± 0.944 5.64 9.04 20
Wing Chord 4.65 ± 0.671 4.0 6.5 20
Culmen 2.14 ± 0.228 1.84 2.9 20
Outer Primary 0 0 0 12
Outer Rectrix 0 0 0 12
Longest Broken Primary 0 0 0 20
Length 36.53 ± 4.128 28.0 46.0 19
Gape 7.46 ± 0.481 6.87 8.88 20
General Description
Eyes closed. Ears are closed, though a small indentation
is visible. Bill is orange/grey with, some brown at the tip
and a yellowish/white rictus. The egg tooth is visible near
the tip of the upper mandible. Skin is a light orange with
some pink areas. Light gray down is present on capital,
dorsal, alar, humeral, and femoral tracts. Eyelids appear
large and dark gray. Ventral tract is visible as indentations
on skin. Dorsal pins are visible as a very light gray stripe.
Capital tract pins very light in color, small, and just visible.
Femoral tract is typically not visible. Humeral tract is
visible as a very light gray single line. Caudal and crural
tracts are not visible. Young able to move all limbs very
slowly and lift head briefly.
Song Sparrow (Melospiza melodia gouldii) continued
Day 2 Key Visual Indicators:
- Alar pins individually distinguishable
- Alar pins stretched towards posterior edge of wing
Feather Tract Development
Tract N V P U F n
Capital 3 97 32
Dorsal 100 32
Humeral 3 97 32
Alar 97 3 32
Femoral 31 69 32
Crural 55 45 31
Caudal 68 32 31
Ventral 6 94 32
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 3.434 ± 0.695 2.5 5.9 32
Tarsus 8.54 ± 1.018 6.06 10.46 32
Wing Chord 5.45 ± 0.766 4.0 8.0 32
Culmen 2.41 ± 0.303 1.42 2.83 32
Outer Primary 0.03 ± 0 0 0.5 16
Outer Rectrix 0 0 0 16
Longest Broken Primary 0 0 0 32
Length 38.91 ± 2.97 35.0 48.0 32
Gape 8.68 ± 0.746 7.23 10.02 32
General Description
Eyes closed. Ears closed. Capital tract visible as gray
flecks. Dorsal pins visible as gray flecks forming a
stripe. Capital tract visible as gray flecks. Alar pins
distinguishable as individual pins. Femoral tract is visible
as a few gray flecks. Humeral tract is visible as a gray
band. Caudal tract is visible as a single gray line. Crural
tract is visible as a few gray flecks. Ventral tract is visible
as gray spotting from furculum to about mid-chest; visible
as skin markings posteriorly. May have small hair-like
protrusions on wing where flight feathers will protrude.
Young are able to quietly chirp and move all limbs.
36 A Guide to Nestling Development and Aging in Altricial Passerines
Day 3 Key Visual Indicators:
- Some to all remiges emerging
- P9 measures about 1mm
Feather Tract Development
Tract N V P U F n
Capital 100 30
Dorsal 97 3 30
Humeral 93 7 30
Alar 17 83 30
Femoral 93 7 30
Crural 7 93 30
Caudal 10 90 30
Ventral 97 3 30
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 5.45 ± 1.157 3.1 9.0 30
Tarsus 10.85 ± 1.417 8.63 14.37 30
Wing Chord 8.15 ± 1.885 5.0 12.0 30
Culmen 2.84 ± 0.273 2.3 3.57 30
Outer Primary 0.75 ± 0.429 0.5 2.0 18
Outer Rectrix 0 0 0 18
Longest Broken Primary 0 0 0 30
Length 42.5 ± 2.968 37.0 49.0 30
Gape 10.24 ± 0.820 7.98 11.77 30
General Description
Eyes closed. Ears closed. Capital tract visible as gray
flecks in a band with smaller flecks around the ear. Dorsal
pins are visible as a gray stripe. Some or all remiges are
emerging. P9 is less than 1mm. Humeral and femoral
tracts darker, still not out. Caudal tract line a bit thicker.
Crural tract pins visible as flecks, still not out. Ventral
tract is visible as gray flecks from furculum to mid-chest.
Some spotting on chin is visible. Pins along belly are light
in color and still not out. Young lifting whole body and
head up with forelimbs and legs.
Song Sparrow (Melospiza melodia gouldii) continued
Day 4 Key Visual Indicators:
- All remiges have emerged
- P9 measures about 2 mm
- Most body pins appear to be just out or pushing up
on skin surface
- Eyes may be partially open
Feather Tract Development
Tract N V P U F n
Capital 85 15 26
Dorsal 58 42 26
Humeral 46 54 26
Alar 100 26
Femoral 80 19 26
Crural 96 4 26
Caudal 96 4 26
Ventral 58 42 26
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 7.64 ± 1.495 3.6 10.3 25
Tarsus 13.44 ± 1.548 10.24 16.65 26
Wing Chord 11.94 ± 1.899 8.0 17.0 26
Culmen 3.27 ± 0.285 2.68 3.96 26
Outer Primary 2.25 ± 0.913 1.0 4.5 16
Outer Rectrix 0 0 0 16
Longest Broken Primary 0 0 0 26
Length 48.0 ± 3.544 40.0 55.0 26
Gape 11.25 ± 0.626 9.53 12.02 26
General Description
Eyes may partially open. Ears open. Most body pins
appear to be out or pushing up against the skin surface. A
few femoral pins may be out or pushing on skin. Humeral
pins are out. All other pins are pushing up on the skin
except for the crural tract. All remiges have emerged.
P9 measures about 2mm. Ventral pins may be just out or
pushing on skin and much more pronounced. Skin color
becoming darker pink. Down is still present. Young are
able to turn over on to back.
Results 37
Day 5 Key Visual Indicators:
- P9 measures about 4mm
- Most pin feathers are out
- Some body pins may begin unsheathing
Feather Tract Development
Tract N V P U F n
Capital 50 50 26
Dorsal 96 4 26
Humeral 100 26
Alar 100 26
Femoral 4 96 26
Crural 58 42 26
Caudal 85 15 26
Ventral 4 92 4 26
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 9.86 ± 1.757 6.0 13.2 21
Tarsus 15.17 ± 1.549 11.44 18.04 26
Wing Chord 15.48 ± 2.012 11.0 22.0 26
Culmen 3.58 ± 0.306 3.02 4.18 26
Outer Primary 4.0 ± 1.676 2.0 8.0 14
Outer Rectrix 0.071 ± 0.182 0 0.5 14
Longest Broken Primary 0 0 0 26
Length 50.75 ± 2.625 46.0 56.0 24
Gape 11.95 ± 0.597 10.7 13.08 26
General Description
Eyes may be opened partially. Capital tract pins are just
out. Dorsal pins are out from nape to about mid-back.
Some crural tract pins are out. Humeral and femoral pins
are out 1 - 2 mm. Caudal tract shows hair-like projections
where the rectrices will emerge. Ventral pins are out about
1 mm. P9 measures about 4 mm. Small subcutaneous pins
are visible around ear and cloaca.
Song Sparrow (Melospiza melodia gouldii) continued
Day 6 Key Visual Indicators:
- P9 measures about 6mm
- All dorsal pins are out
Feather Tract Development
Tract N V P U F n
Capital 4 96 26
Dorsal 62 38 26
Humeral 54 46 26
Alar 92 8 26
Femoral 4 42 54 26
Crural 4 73 23 26
Caudal 23 77 26
Ventral 35 65 26
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 11.73 ± 2.396 3.3 14.7 26
Tarsus 17.62 ± 2.032 12.05 20.74 26
Wing Chord 19.92 ± 3.215 11.0 24.0 26
Culmen 3.92 ± 0.404 2.91 4.62 26
Outer Primary 7.43 ± 2.065 3.5 10.0 14
Outer Rectrix 1.07 ± 0.829 0 2.0 14
Longest Broken Primary 0.038 ± 0.196 0 1.0 26
Length 54.46 ± 4.101 42.0 65.0 26
Gape 12.30 ± 0.744 9.97 13.31 26
General Description
Eyes open. Capital tract pins are out about 1mm. Dorsal
pins are out from nape to tail bud. Most crural tract pins
are out. Humeral and femoral pins are out about 2 mm.
Pins around ear are just emerging. Rectrices may be just
emerging. Ventral pins are out about 2 mm. P9 measures
about 6 mm. Tips of primaries may appear whitish and
ready to break
38 A Guide to Nestling Development and Aging in Altricial Passerines
Day 7 Key Visual Indicators:
- Flight feathers have begun to unsheathe
- All feather tracts are unsheathing
- Eyes may appear fully open
Feather Tract Development
Tract N V P U F n
Capital 56 44 25
Dorsal 8 92 25
Humeral 4 96 25
Alar 24 76 25
Femoral 4 96 25
Crural 28 72 25
Caudal 8 56 36 25
Ventral 4 96 25
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 13.80 ± 1.641 9.2 15.7 26
Tarsus 19.66 ± 1.778 14.85 22.13 27
Wing Chord 24.35 ± 3.059 17.0 30.0 26
Culmen 4.38 ± 0.333 3.7 5.05 27
Outer Primary 10.69 ± 2.462 5.0 15.0 16
Outer Rectrix 2.91 ± 1.725 0 6.0 16
Longest Broken Primary 0.796 ± 1.031 0 4.0 27
Length 58.13 ± 4.174 54.0 70.0 24
Gape 12.34 ± 0.535 11.13 13.36 27
General Description
Dorsal pins are about 30% unsheathing. Capital tract pins
are about 2 mm. Some crural pins are unsheathing. Some
femoral pins are unsheathing. Most humeral pins are
unsheathing. Flight feathers have begun to unsheathe.
Ventral pins are mostly unsheathed with the exception of
the throat area. Young are typically ready for banding.
Young are prone to “jump” after this day.
Song Sparrow (Melospiza melodia gouldii) continued
Results 39
Species Accounts
Chestnut-collared Longspur
Calcarius ornatus
Data collection: Bowdoin National Wildlife Refuge, Phillips County, Montana. Nests: n = 1 (2004), n = 1
(2005), n = 5 (2006)
Nest Period Data: Average (range), n = number of nests
Building: no data
Clutch size: 4.1 (1 - 7) eggs, n = 764
Incubation: 11.0 (7 - 15) days, n = 553
Nestling: 11.3 (7 - 15) days, n = 166
Indicator Table: Chestnut-collared Longspur visual characteristics typical at a given age.
No feather tracts are visible 1
Alar, dorsal, and ventral tracts becoming visible 2
Alar pins have grown towards posterior edge of
wing and pressing on skin surface 3
Eyes begin to open. Alar pins typically emerged 4
Pin feathers have emerged on all tracts 5
Pins begin to unsheathe. Primary tips pale and ready to
unsheathe 6
Primary pins begin to unsheathe 7
All feather tracts are unsheathing 8
Indicator characteristics Age Indicator characteristics Age
General Feather Development: Chestnut-collared Longspur feather tract development by day. Most advanced
stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing,
or F-Fully unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N N N N N N N N V
2 N N V N N V N N N N V
3 N V N V N V N V P N V N V N V V P
4 N V N V P N V P N V P V P N V P N V P V P
5 N V P V P V P V P V P N V P N V P V P
6 V P U P U P U P U P U V P U V P P U
7 P U P U P U P U U P U P U P U
8 U U U U U U U U
40 A Guide to Nestling Development and Aging in Altricial Passerines
Chestnut-collared Longspur (Calcarius ornatus) continued
Day 1 Key Visual Indicators:
- Down may appear wet or clumped together
- Eyes closed
- Nestling may be curled into a ball
Feather Tract Development
Tract N V P U F n
Capital 100 8
Dorsal 100 8
Humeral 100 8
Alar 100 8
Femoral 100 8
Crural 100 8
Caudal 100 8
Ventral 88 12 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 2.12 ± 0.41 1.7 2.8 9
Tarsus 6.75 ± 0.67 5.93 7.94 9
Wing Chord 5.78 ± 0.87 4.5 7.0 9
Culmen 2.29 ± 0.14 2.1 2.5 9
Outer Primary 0 0 0 10
Outer Rectrix 0 0 0 10
Longest Broken Primary 0 0 0 10
Length 35.0 ± 1.91 33.0 38.0 7
Gape 7.92 ± 0.74 6.85 8.9 7
General Description
Eyes and ears are closed. Skin and legs flesh colored with
orange tinge (salmon). All feather tracts are usually not
visible though areas around feather tracts may appear
slightly darker or as stippling of skin surface. Skin lighter
on ventral side and legs. Light grey/tan down on all
feather tracts except ventral. Down approx. 5 mm long
and may be wet or clumped together. Pale bill with white
rictus. Ear canal appears as a shallow indentation. May
display weak, shaky gaping and weak forward movement.
Can’t hold head up. Lays flat on belly or may curl into ball
shape. Very rarely makes very soft chirping sound, most
made no noise.
Day 2 Key Visual Indicators:
- Some feather tracts (alar, dorsal, and ventral)
becoming visible as darker areas or very small
dark spots
Feather Tract Development
Tract N V P U F n
Capital 100 10
Dorsal 60 40 10
Humeral 100 10
Alar 50 50 10
Femoral 100 10
Crural 100 10
Caudal 100 10
Ventral 40 60 10
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 3.16 ± 0.78 1.9 4.7 10
Tarsus 7.90 ± 0.69 6.62 8.91 10
Wing Chord 6.96 ± 1.34 4.9 9.0 8
Culmen 2.50 ± 0.29 1.82 2.8 9
Outer Primary 0 0 0 9
Outer Rectrix 0 0 0 10
Longest Broken Primary 0 0 0 10
Length 38.7 ± 1.83 37.0 43.0 10
Gape 8.66 ± 0.69 7.4 9.77 10
General Description
Appearance very much the same as first day except that
skin appears slightly darker and some pins are becoming
visible. Subcutaneous alar pins are becoming visible.
Dorsal tract may be visible as darker area or very small
dark spots. Ventral pins not pigmented. Position and
movement the same as day one. Can’t hold head up and
may still curl into ball shape.
Results 41
Day 3 Key Visual Indicators:
- Dorsal and capital tracts becoming darker (gray)
- Pins may be emerging on alar tract
Feather Tract Development
Tract N V P U F n
Capital 15 85 13
Dorsal 8 92 13
Humeral 31 69 13
Alar 15 54 31 13
Femoral 31 69 13
Crural 54 46 13
Caudal 77 23 13
Ventral 92 8 13
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 4.49 ± 0.84 2.6 5.9 13
Tarsus 9.51 ± 1.05 6.89 11.19 13
Wing Chord 8.3 ± 1.10 6.5 10.3 13
Culmen 2.90 ± 0.34 2.25 3.4 13
Outer Primary 0.25 ± 0.45 0 1.0 12
Outer Rectrix 0 0 0 13
Longest Broken Primary 0 0 0 13
Length 43.45 ± 2.34 39.0 48.0 11
Gape 9.82 ± 0.71 8.19 10.93 13
General Description
Eyes are closed. Ear canal is larger. Skin less orange and
darker overall with dark gray areas at feather tracts.
Pins may be emerging on alar tracts. Dorsal and capital
tracts becoming darker gray. Dorsal tract forms a dark
gray stripe along back. Ventral tract is clearly visible and
may be pressing up on skin. Gape orange-red with white
rictus. May be gaping at noises and holds head up for a
few seconds. Movement weak but steadier. Can right itself
with some effort. Quiet.
Chestnut-collared Longspur (Calcarius ornatus) continued
Day 4 Key Visual Indicators:
- Eyes begin to open
- Most feather tracts visible
- Alar pins have typically emerged 1-2 mm
Feather Tract Development
Tract N V P U F n
Capital 9 91 11
Dorsal 54 45 11
Humeral 9 55 36 11
Alar 18 82 11
Femoral 64 36 11
Crural 28 36 36 11
Caudal 27 64 9 11
Ventral 64 36 11
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 6.43 ± 1.31 3.7 8.5 11
Tarsus 11.50 ± 1.37 8.64 13.36 11
Wing Chord 11.5 ± 2.17 9.0 16.0 10
Culmen 3.28 ± 0.34 2.6 3.7 11
Outer Primary 1.56 ± 0.82 0.5 3.0 8
Outer Rectrix 0 0 0 13
Longest Broken Primary 0 0 0 13
Length 48.44 ± 3.32 41.0 53.0 9
Gape 10.81 ± 0.76 9.2 11.81 11
General Description
Eyes may be partially open. Ear canal appears open. Skin
around dorsal tract appears reddish. Ventral side and legs
flesh colored. All feather tracts except caudal are visible
and may be pressing up on skin. Alar pins have typically
emerged. Still downy on all tracts except ventral; caudal
down very sparse or absent. Gaping longer and overall
movement is stronger. Rights itself in a few seconds
and weakly scoots forward with legs. Some soft noises
including soft clicking noises.
42 A Guide to Nestling Development and Aging in Altricial Passerines
Day 5 Key Visual Indicators:
- Eyes partially to fully open
- Pin feathers are typically out on all tracts
- Movement is strong and nestling may balance on
rump and tarsus
Feather Tract Development
Tract N V P U F n
Capital 8 23 69 13
Dorsal 15 85 13
Humeral 15 85 13
Alar 8 92 13
Femoral 15 85 13
Crural 15 15 70 13
Caudal 8 30 62 13
Ventral 31 69 13
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 8.88 ± 1.29 6.2 11.2 13
Tarsus 14.09 ± 1.21 12.26 15.77 13
Wing Chord 16.27 ± 2.57 11.0 21.5 13
Culmen 3.74 ± 0.23 3.38 4.1 13
Outer Primary 3.95 ± 2.31 1.5 9.0 10
Outer Rectrix 0.35 ± 0.55 0 1.5 13
Longest Broken Primary 0 0 0 13
Length 53.91 ± 1.51 51.0 56.0 11
Gape 11.73 ± 0.65 10.3 12.8 13
General Description
Eyes at least partially open. Skin appears the same
color as day four. Pins are typically emerging on all
feather tracts but unsheathing has not yet begun. Down
still present but more sparse. More frequent, stronger
movement and may balance on rump and tarsus. More
frequent and louder chirping noises.
Chestnut-collared Longspur (Calcarius ornatus) continued
Day 6 Key Visual Indicators:
- Pins may be unsheathing on all feather tracts
except caudal
- Eyes may appear fully open
- Primary tips appear pale and ready to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 9 82 9 11
Dorsal 64 36 11
Humeral 55 45 11
Alar 64 36 11
Femoral 36 64 11
Crural 9 64 27 11
Caudal 9 91 11
Ventral 55 45 11
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 10.18 ± 1.56 7.7 11.7 11
Tarsus 15.76 ± 1.34 12.86 17.33 11
Wing Chord 20.18 ± 2.48 16.0 23.0 11
Culmen 4.03 ± 0.31 3.58 4.6 11
Outer Primary 6.73 ± 1.79 4.0 9.0 11
Outer Rectrix 1.09 ± 0.70 0 2.0 11
Longest Broken Primary 0 0 0 11
Length 58.11 ± 3.22 55.0 66.0 9
Gape 12.37 ± 0.63 11.08 13.13 11
General Description
Eyes are fully open. Feathers may be beginning to
unsheathe on all tracts except caudal and capital. Tips of
primaries appear pale and ready to unsheathe. Tips of
wing coverts may appear tan colored if unsheathed. Down
still present. Movement is strong, holds head up. Makes
chirping noises as well as occasional harsher, louder chips.
Results 43
Day 7 Key Visual Indicators:
- Primaries may begin to unsheathe
- Holds head up almost constantly
Feather Tract Development
Tract N V P U F n
Capital 45 55 9
Dorsal 22 88 9
Humeral 45 55 9
Alar 11 89 9
Femoral 100 9
Crural 22 78 9
Caudal 78 22 9
Ventral 11 89 9
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 12.01 ± 2.85 7.0 14.7 9
Tarsus 17.76 ± 1.41 15.2 19.69 9
Wing Chord 25.33 ± 4.85 18.0 33.0 9
Culmen 4.39 ± 0.36 3.8 4.9 9
Outer Primary 10.22 ± 2.28 7.0 14.0 9
Outer Rectrix 2.67 ± 1.22 1.0 5.0 9
Longest Broken Primary 0.44 ± 0.53 0 1.0 9
Length 63.71 ± 4.96 58.0 70.0 7
Gape 12.40 ± 0.61 11.33 13.27 9
General Description
Sparse down. All feather tracts are typically unsheathing
except caudal. Primaries are beginning to unsheathe.
Apteria are obscured by pin feathers along back and
flanks. Moves more frequently and appears alert. Holds
head up almost constantly. Young are typically ready for
banding.
Chestnut-collared Longspur (Calcarius ornatus) continued
Day 8 Key Visual Indicators:
- Primaries unsheathing 2-3 mm
- All feather tracts are unsheathing
Feather Tract Development
Tract N V P U F n
Capital 100 4
Dorsal 100 4
Humeral 100 4
Alar 100 4
Femoral 100 4
Crural 100 4
Caudal 100 4
Ventral 100 4
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 14.9 ± 0.90 14 16.1 4
Tarsus 18.98 ± 0.68 18.06 19.65 4
Wing Chord 31.0 ± 3.27 27.0 35.0 4
Culmen 4.52 ± 0.27 4.26 4.8 4
Outer Primary 13.5 ± 2.52 10.0 16.0 4
Outer Rectrix 3.75 ± 0.50 3.0 4.0 4
Longest Broken Primary 2.25 ± 0.96 1.0 3.0 4
Length 67.75 ± 5.91 60.0 74.0 4
Gape 12.48 ± 0.21 12.18 12.68 4
General Description
All feather tracts unsheathing. Primaries typically
unsheathed 2-3 mm. Unsheathed wing coverts form
light tan wing bars. Most feathers out to the extent that
sheaths may not be visible under feathers and young
appear feathered. More active, controlled movements and
chirping noises given.
44 A Guide to Nestling Development and Aging in Altricial Passerines
Species Accounts
American Goldfinch
Cardeulis tristis
Data collection: Point Reyes National Seashore, Marin County, California. Nests: n = 4 (2004), n = 2 (2005).
Nest Period Data: Average (range), n = number of nests
Building: no data
Clutch size: 4.9 (4 - 6) eggs, n = 55
Incubation: 11.5 (10 - 17) days, n = 16
Nestling: 13.5 (11 - 16) days, n = 15
Indicator Table: American Goldfinch visual characteristics typical at a given age.
Alar pins are very light in color and difficult to see 1
Alar pins are light in color and centered
across the dorsal wing surface 2
Dorsal tract is visible as light gray pins 3
Eyes begin to open 4-5
Alar pins have grown to posterior edge of wing
and appear ready to emerge 4
Alar pins begin to emerge 5
Contour feather pins begin to emerge 6
Ventral tract has begun to unsheathe 7
Most contour feather tracts have begun to unsheathe 8
Primary pins begin to unsheathe 8-9
Capital tract pins are unsheathing 10
Young appear soft due to extent of unsheathing 11
Young appear very alert and can hop on the ground 11
Indicator characteristics Age Indicator characteristics Age
General Feather Development: American Goldfinch feather tract development by day. Most advanced stage
is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or
F-Fully unsheathed.
Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral
1 N N N N V N N N N
2 N N V N V V N N N N
3 N V N V N V V N V N N V N V
4 V V V V V N V N V V
5 V V V P V V V V P
6 V V P V P P V P V P V P V P
7 V P P P P P U V P V P P U
8 P P U P U P U U P U P U U
9 P U U U U U U P U U
10 U U U U U U U U
11 U U U U U U U U
45
Day 1 Key Visual Indicators:
- Young are egg size and down may be matted
- Alar pins are very light in color and difficult to see
- No other pigmented pins are visible
Feather Tract Development
Tract N V P U F n
Capital 100 6
Dorsal 100 6
Humeral 100 6
Alar 33 67 6
Femoral 100 6
Crural 100 6
Caudal 100 6
Ventral 100 6
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 1.23 ± 0.288 0.8 1.6 6
Tarsus 4.34 ± 0.214 4.13 4.67 6
Wing Chord 4.0 ± 0.316 3.5 4.5 6
Culmen 2.08 ± 0.117 1.91 2.21 6
Outer Primary 0 0 0 6
Outer Rectrix 0 0 0 6
Longest Broken Primary 0 0 0 6
Length 29.08 ± 2.764 25.5 33 6
Gape 5.64 ± 0.297 5.15 5.97 6
General Description
Eyes are closed. Ear is closed and visible as an
indentation. Bill is yellow-orange with a violet-pink gape.
Light colored down is present on the capital, dorsal,
humeral, alar, femoral, and crural tracts and may be
matted. Alar pins may be visible but are very light in color.
No other feather tracts are visible. Young are egg size and
weigh less than 2 grams.
American Goldfinch (Cardeulis tristis) continued
Day 2 Key Visual Indicators:
- Alar pins are light in color and centered across the
dorsal surface of wing
- No other feather tracts are readily apparent
Feather Tract Development
Tract N V P U F n
Capital 100 8
Dorsal 75 25 8
Humeral 87.5 12.5 8
Alar 100 8
Femoral 100 8
Crural 100 8
Caudal 100 8
Ventral 100 7
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 2.05 ± 0.307 1.6 2.5 8
Tarsus 5.25 ± 0.406 4.6 5.72 8
Wing Chord 4.69 ± 0.372 0 5.0 8
Culmen 2.39 ± 0.076 2.32 2.52 8
Outer Primary 0 0 0 8
Outer Rectrix 0 0 0 8
Longest Broken Primary 0 0 0 8
Length 32.88 ± 2.031 31.0 36.0 8
Gape 6.55 ± 0.422 6.01 7.22 8
General Description
Eyes are closed. Alar pins are visible as very light pins
centered across the dorsal surface of wing. Ventral tract
is not pigmented but appears as stippling on skin surface.
No other tracts are visible.
Results
46 A Guide to Nestling Development and Aging in Altricial Passerines
Day 3 Key Visual Indicators:
- Alar pins have grown towards posterior edge of
wing
- Dorsal tract is visible as very light gray pins
- Skin around head and dorsal surface begins to
darken
Feather Tract Development
Tract N V P U F n
Capital 80 20 10
Dorsal 10 90 10
Humeral 50 50 10
Alar 100 10
Femoral 60 40 10
Crural 100 10
Caudal 60 40 10
Ventral 70 30 10
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 2.58 ± 0.437 1.6 3 8
Tarsus 7.01 ± 1.026 5.92 8.94 10
Wing Chord 5.2 ± 1.033 3.0 6.0 10
Culmen 2.76 ± 0.127 2.55 2.99 10
Outer Primary 0 0 0 10
Outer Rectrix 0 0 0 10
Longest Broken Primary 0 0 0 10
Length 36.9 ± 2.283 32.0 40.0 10
Gape 7.08 ± 0.409 6.48 7.56 10
General Description
Eyes closed. Alar pins have grown towards posterior edge
of wing. Dorsal tract is visible as light gray pins. Humeral
tract may be visible. Caudal tract may just be visible.
Ventral tract is visible as unpigmented stippling. Abdomen
is enlarged and darkening.
American Goldfinch (Cardeulis tristis) continued
Day 4 Key Visual Indicators:
- Alar pins have grown to the posterior edge of wing
and appear ready to emerge
- Hair-like projections appear where alar pins will
emerge
Feather Tract Development
Tract N V P U F n
Capital 100 6
Dorsal 100 6
Humeral 100 6
Alar 100 6
Femoral 100 6
Crural 67 33 6
Caudal 17 83 6
Ventral 100 6
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 3.54 ± 0.688 2.4 4.1 5
Tarsus 8.95 ± 0.830 7.44 9.85 6
Wing Chord 6.92 ± 0.970 5.0 7.5 6
Culmen 3.11 ± 0.111 2.92 3.24 6
Outer Primary 0 0 0 6
Outer Rectrix 0 0 0 6
Longest Broken Primary 0 0 0 6
Length 41.67 ± 2.875 37.0 45.0 6
Gape 8.03 ± 0.654 6.74 8.51 6
General Description
Eyes may be partially opened. Ear canal may be partially
open. Capital tract is just becoming visible and area is
darkening. Dorsal tract area is darkening. Alar pins have
grown to the edge of wing and appear ready to emerge.
Hair-like projections appear where alar pins will emerge.
Humeral tract visible as gray flecks. Ventral tract visible
as gray flecks near the chest and as flesh colored stippling
across the sides of the abdomen.
Results 47
Day 5 Key Visual Indicators:
- Alar tract pins have emerged or just emerged
- Capital, dorsal, and humeral tracts are dark, but no
pins have emerged
Feather Tract Development
Tract N V P U F n
Capital 100 8
Dorsal 100 8
Humeral 100 8
Alar 100 8
Femoral 100 8
Crural 100 8
Caudal 100 8
Ventral 87.5 12.5 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 5.11 ± 0.582 4.4 6.2 8
Tarsus 10.19 ± 1.288 8.43 12.12 8
Wing Chord 11.38 ± 1.706 8.0 14.0 8
Culmen 3.55 ± 0.088 3.34 3.63 8
Outer Primary 0.94 ± 0.417 0.5 1.5 8
Outer Rectrix 0 0 0 8
Longest Broken Primary 0 0 0 8
Length 45.38 ± 3.114 41.0 51.0 8
Gape 8.49 ± 0.295 8.13 8.99 8
General Description
Eyes are partially open. Capital tract is dark. Dorsal
tract is dark and appears as a gray strip along the spine.
Humeral and femoral tracts visible as a gray strip. Some
alar pins have emerged. Crural tract visible as a few gray
flecks. Seed stored in crop may be apparent.
American Goldfinch (Cardeulis tristis) continued
Day 6 Key Visual Indicators:
- Alar pins are 2-3mm in length
- Most contour feather pins have just emerged or
have tips pressing up on skin surface
Feather Tract Development
Tract N V P U F n
Capital 100 10
Dorsal 30 70 10
Humeral 30 70 10
Alar 100 10
Femoral 30 70 10
Crural 90 10 10
Caudal 90 10 10
Ventral 30 70 10
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 6.09 ± 0.723 4.4 7.1 10
Tarsus 11.60 ± 0.774 10.37 12.96 10
Wing Chord 15.15 ± 1.717 11.0 17.0 10
Culmen 3.85 ± 0.199 3.45 4.15 10
Outer Primary 2.85 ± 0.883 0.5 3.5 10
Outer Rectrix 0.05 ± 0.158 0 0.5 10
Longest Broken Primary 0 0 0 10
Length 48.35 ± 3.496 41.0 54.0 10
Gape 8.82 ± 0.288 8.34 9.22 10
General Description
Dorsal, humeral, femoral, and ventral tracts have
darkened and are just emerging. Primary, secondary,
and some covert alar pins have emerged. Alar pins have
emerged 2-3mm. Femoral pins have lengthened and may
have emerged. Hair-like projections appear where caudal
pins will emerge.
48 A Guide to Nestling Development and Aging in Altricial Passerines
Day 7 Key Visual Indicators:
- Dorsal, humeral, and caudal tracts have emerged by
1-2 mm
- Ventral tract has just begun to unsheathe
Feather Tract Development
Tract N V P U F n
Capital 87.5 12.5 8
Dorsal 100 8
Humeral 100 8
Alar 100 8
Femoral 75 25 8
Crural 12.5 87.5 8
Caudal 12.5 87.5 8
Ventral 37.5 62.5 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 7.03 ± 0.634 5.8 7.8 8
Tarsus 13.09 ± 0.731 12.27 14.64 8
Wing Chord 19.19 ± 1.963 15.0 21.5 8
Culmen 4.10 ± 0.156 3.76 4.25 8
Outer Primary 5.5 ± 1.282 2.5 6.5 8
Outer Rectrix 0.688 ± 0.372 0 1.0 8
Longest Broken Primary 0 0 0 8
Length 51.13 ± 4.581 42.0 58.0 8
Gape 8.99 ± 0.582 7.91 9.59 8
General Description
Eyes appear fully open. Capital tract pushing up on
skin. All other tracts have emerged. Dorsal and humeral
tract pins are out 1-2 mm. Ventral pins are typically
unsheathing. Caudal pins are just emerged.
American Goldfinch (Cardeulis tristis) continued
Day 8 Key Visual Indicators:
- Some wing coverts have begun to unsheathe
- Capital tract pins have typically begun to emerge
- Most contour feather tracts have begun to un
sheathe
Feather Tract Development
Tract N V P U F n
Capital 100 10
Dorsal 10 90 10
Humeral 10 90 10
Alar 20 80 10
Femoral 100 10
Crural 10 90 10
Caudal 80 20 10
Ventral 100 10
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 8.34 ± 0.938 6.2 9.8 10
Tarsus 13.19 ± 0.721 11.96 14.23 10
Wing Chord 23.65 ± 2.310 18.0 26.0 10
Culmen 4.48 ± 0.201 4.19 4.87 10
Outer Primary 8.7 ± 1.418 5.0 10.0 10
Outer Rectrix 1.95 ± 0.762 0.5 3.0 10
Longest Broken Primary 0.25 ± 0.354 0 1.0 10
Length 55.5 ± 3.274 48.0 59.0 10
Gape 9.17 ± 0.650 8.01 9.95 10
General Description
Capital tract pins have emerged. Some dorsal, humeral,
femoral, and crural tract pins unsheathing. Some wing
coverts unsheathing. Primary and secondary pin tips
appear white and ready to unsheathe or have just begun
to unsheathe. Most ventral tract pins are unsheathing.
Young can stand up on tarsus. Young are typically ready
for banding.
Results 49
Day 9 Key Visual Indicators:
- Most primary pins have begun to unsheathe
- Most contour feather pins (except capital) are un
sheathing at tips
Feather Tract Development
Tract N V P U F n
Capital 50 50 8
Dorsal 100 8
Humeral 100 8
Alar 100 8
Femoral 100 8
Crural 100 8
Caudal 12.5 87.5 8
Ventral 100 8
Morphometric Data
Measurements Mean ± SD Min Max n
Weight 9.09 ± 0.869 7.5 10.2 8
Tarsus 14.15 ± 0.669 13.54 15.19 7
Wing Chord 26.19 ± 2.137 22.0 29.0 8
Culmen 4.64 ± 0.180 4.3 4.91 8
Outer Primary 11.69 ± 1.624 8.0 13.0 8
Outer Rectrix 3.63 ± 1.188 1.0 5.0 8
Longest Broken Primary 1.56 ± 0.729 0 2.0 8
Length 57.25 ± 3.775 52.0 60.0 4
Gape 9.36 ± 0.447 8.94 10.14 8
General Description
Capital tract pins may be unsheathing. Most dorsal,
humeral, crural, and femoral pins are unsheathing and
have light cinnamon tips. Alar pins unsheathed 1-2 mm.
Caudal pins have begun to unsheathe. Young appear alert.
America
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| Rating | |
| Title | A guide to nestling development and aging in altricial passerines |
| Contact | mailto:library@fws.gov |
| Creator | Jongsomjit, Dennis; Jones, Stephanie L; Gardali, Thomas; Geupel, Geoffry R.; Gouse, Paula J. |
| Description | This is a guide to altricial passerines. It has an explanation of variables used for aging birds and an explanation of methodology employed, and provides information obtained while recording the early aging of the Dusky Flycatcher, the Carolina Wren, the Wrentit, Sprague’s Pipit, the Song Sparrow, the Chestnut-collared Longspur and the American Goldfinch. |
| Subject |
Birds Perching birds Research Statistics |
| Publisher | U.S. Fish and Wildlife Service |
| Date of Original | 2007-10 |
| Type | Text |
| Format | |
| Item ID | BTP\altricialpasserines07.pdf |
| Source | NCTC Conservation Library |
| Language | English |
| Rights | Public domain |
| Audience | General |
| File Size | 843 KB |
| Original Format | Digital |
| Length | 66 p. |
| Transcript | U.S Fish & Wildlife Service A Guide to Nestling Development and Aging in Altricial Passerines Biological Technical Publication BTP-R6008-2007 U.S Fish & Wildlife Service A Guide to Nestling Development and Aging in Altricial Passerines Biological Technical Publication BTP-R6008-2007 Dennis Jongsomjit1 Stephanie L. Jones2 Thomas Gardali1 Geoffrey R. Geupel1 Paula J. Gouse3 1 PRBO Conservation Science, Petaluma, CA 2 U.S. Fish and Wildlife Service, Region 6, Office of Migratory Birds, Denver, CO 3 U.S. Fish and Wildlife Service, Bowdoin National Wildlife Refuge, Malta, MT Cover images: Top: Crissal Thrasher, Toxostoma crissale Bottom: Brewer’s Sparrow, Spizella breweri Photo credits: Top: Chris McCreedy/PRBO Bottom: Colin Wooley/PRBO ii A Guide to Nestling Development and Aging in Altricial Passerines Author contact information: Dennis Jongsomjit PRBO Conservation Science 3820 Cypress Drive Petaluma, CA 94954 707-781-2555 email:djongsomjit@prbo.org Stephanie L. Jones U.S. Fish and Wildlife Service, Region 6 Nongame Migratory Birds P.O. Box 25486 DFC Denver, CO 80225 303-236-4409 Email: stephanie_jones@fws.gov Thomas Gardali PRBO Conservation Science 3820 Cypress Drive Petaluma, CA 94954 415-868-0655 x 381 Email: tgardali@prbo.org Geoffrey R. Geupel PRBO Conservation Science 3820 Cypress Drive Petaluma, CA 94954 415-868-0655 x 301 Email: ggeupel@prbo.org Paula J. Gouse U.S. Fish and Wildlife Service Bowdoin National Wildlife Refuge 194 Bowdoin Auto Tour Rd Malta, MT 59538 406-654-2863 Email: paula_gouse@fws.gov For additional copies or information contact: U.S. Fish and Wildlife Service, Region 6 Nongame Migratory Bird Program P.O. Box 25486 DFC Denver, CO 80225-0486 Recommended citation: Jongsomjit, D., S. L. Jones, T. Gardali, G. R. Geupel, and P. J. Gouse. 2007. A guide to nestling development and aging in altricial passerines. U.S. Department of Interior, Fish and Wildlife Service, Biological Technical Publication, FWS/BTP-R6008- 2007, Washington, D.C. Table of Contents iii Table of Contents List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Nestling Growth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Analyzing Growth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Growth Patterns and Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Aging Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Variables Used for Aging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Individual feather tracts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Wing chord. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Tarsus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Primary and rectrices pin lengths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Culmen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Eyes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Longest broken primary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Total body length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Gape and rictus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Physical and behavioral descriptors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Using the Species Accounts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Measurements and Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Feather definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Tarsus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Wing chord. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Primary and rectrix pin length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Culmen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Total length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Longest broken primary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Gape and rictus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Physical and behavioral descriptors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Species Account Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Species information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Indicator table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 General feather development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Key visual indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Photographs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Feather tract data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Morphometric data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 General description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Species Accounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Dusky Flycatcher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Carolina Wren. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Wrentit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Sprague’s Pipit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Song Sparrow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Chestnut-collared Longspur. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 American Goldfinch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Appendix A. Adult Morphometric Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Appendix B. Data Collection Methods and Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 iv A Guide to Nestling Development and Aging in Altricial Passerines List of Figures Figure 1. Dorsal and ventral views of a nestling with the individual feather tracts marked and identified. . . . .5 Figure 2. Tarsus with measurement indicators at the tibiotarsus joint and distal end of the last leg scale . . 6 Figure 3. Wing chord as measured with a wing ruler, without flattening or pressing down on the wing .. . . . . 6 Figure 4. Pin lengths as measured from the point of emergence from the skin . . . . . . . . . . . . . . 6 Figure 5. The culmen as measured from nares to tip . . . . . . . . . . . . . . . . . . . . . . . . . 6 Figure 6. Total body length taken from the tip of the bill to the tail bud . . . . . . . . . . . . . . . . . 6 Figure 7. The exposed portion of the longest broken primary as measured with a ruler. . . . . . . . . . . . . . . . . . . .6 Figure 8. The gape as measured with calipers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Figure 9. Examples of feather development and appearance using a Wrentit on Day 7 . . . . . . . . . . 7 Figure B-1. An example of systematic labeling of data sheets and photographs which uniquely identifies each nestling and their age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Acknowledgments v Acknowledgments The collection of data for this guide would not have been possible without the help of many interns and field biologists including Parvaneh C. Abbaspour, Bethany S. Atchley, Amon J. Armstrong, Ross R. Conover, Gerhard A. Epke, Tristan R. Gingerich, Geetha M. Jayabose, Scott F. Jennings, Laura H. Kaplan, Errin B. Kramer-Wilt, Ben G. Larson, Blaine MacDonald, Emily Morrison, Henry Ndithia, Kerry E. Neijstrom, Alexander Rosenthal, Corrina Snow, Amanda B. Shults, and Dionne R. Wrights. Many thanks to Suzanne Austin-Blythell, Bruce Barbour, Thomas M. Haggerty, Steve N. G. Howell, and Diana L. Humple for providing helpful comments to earlier drafts of this guide. Fig. 1 is adapted from Gill (1994) and Fig. 6 is adapted from Baldwin et al. (1931). We thank Peter Pyle and Steve N. G. Howell for graciously allowing us the use of Figs. 2, 3, and 5 (Pyle 1997). Figures 4, 7, and 8 were drawn by Dennis Jongsomjit. We thank the Point Reyes National Seashore for their continued cooperation. Funding was provided by the U.S. Fish and Wildlife Service Region 6 Nongame Migratory Bird Program. This is PRBO contribution 1603. Data Contributors We especially thank the colleagues that contributed nestling data to this publication: Ryan Burnett and Vanessa Tissdale – PRBO Conservation Science, Dusky Flycatcher (Empidonax oberholseri) and Thomas M. Haggerty – Department of Biology, University of North Alabama, Carolina Wren (Thryothorus ludovicianus). 1 Nestling growth and development studies have been a topic of interest for a greater part of the last century (Sutton 1935, Walkinshaw 1948) and continue to be of interest today. This is not surprising since studies on nestling growth can provide a wealth of biological information that has larger implications for avian management and conservation. Despite this history of studying nestling development, basic information is still limited or absent for many species. Many questions remain unanswered, and contradictory conclusions are often found in the literature (Starck and Ricklefs 1998a). Therefore, much information on aging and development can still be gained from studying the development patterns of similar species and from comparative studies, across avian orders (Minea et al. 1982, Saunders and Hansen 1989, Carsson and Hörnfeldt 1993). Additionally, nestling growth studies can yield insight into the effects of different nesting strategies on productivity (O’Connor 1978), as well as the impacts of parental effort and environmental variables on fitness (Ross 1980, Ricklefs and Peters 1981, Magrath 1991). Since low reproductive success may play a significant role in the declines of many North American passerines (Sherry and Holmes 1992, Ballard et al. 2003), a better understanding of the factors that influence reproductive success is a vital component of avian conservation (Martin 1992). Data on nestling aging can be used to improve nest survival estimates (Dinsmore 2002, Nur et al. 2004), providing information that can be used to more precisely age nests (Pinkowski 1975, Podlesack and Blem 2002), (Jones and Geupel 2007). Indeed, the relatively short time period young spend developing in the nest is a critical part of a bird’s life cycle and a nestling’s developmental path can affect its survival to independence, its survival as an adult, and its future reproductive success. Nestling Growth Ornithologists categorize birds over an altricial to precocial spectrum, based on differences in the rate of growth and type of development young birds will undertake (Starck and Ricklefs 1998b). Placement into this spectrum depends on various broad characteristics such as mobility, feeding behavior, presence of down, and parental nest attendance (Gill 1994). Growth rates are highly variable within the altricial to precocial spectrum, with developmental periods varying as much as 30-fold (Ricklefs 1983). Much of this variation in growth can be attributed, at the phylogenetic level, to differences in body mass. In general, altricial species can grow at 3-4 times the rate of precocial species, and growth rates of birds with similar mass can vary by as much as a factor of 10 (Ricklefs et al. 1998). In this guide, we focus on altricial species. Nestling growth variability has largely been studied looking at effects on individual fitness of offspring and parents (e.g., Murphy 1983, Magrath 1991, Halupka 1998). Differences between populations can manifest as morphological differences or differential timing in the growth and maturation of certain body components (Murphy 1983, Burns 1993). However, the growth rate of a single species throughout its entire range can sometimes vary little (King and Hubbard 1981, Murphy 1983, Pereyra and Morton 2001). Variability in nestling growth rates can be due to many ecological factors, in conjunction with specific species life history strategies; some developmental processes might be linked and are also independent of the nutritional state of a nestling (Ricklefs 1968a). Some factors associated with species specific growth rates and patterns include nest location, synchronicity of hatching, and brood size (Murphy 1983). Ecological factors that influence nestling growth are generally related to limitations in food availability (Ricklefs 1993), including weather (Petersen et al. 1986), habitat differences and quality (Ross 1980, Dawson and Bidwell 2005), parasites (Burhans et al. 2000), competition between nest mates (Werschkul and Jackson 1979, Ricklefs 1982), and parental abilities (Briskie 1995). Additionally, higher nest-predation rates may favor higher nestling growth rates (Lack 1968, Remes and Martin 2002, but see Ricklefs 1969). At the physiological level, an important factor thought to limit growth is “tissue level constraint”, where nestlings are growing at a maximum rate allowable by the tradeoff existing between resources available for growth and mature tissue function (Ricklefs et al. 1998). Once certain types of cells differentiate into mature functioning tissue, they no longer continue to grow (O’Connor 1984). After a period of below normal growth, a nestling would need to increase its growth rate in order to “catch up” to its normal developmental timing. However, such compensatory growth has not been shown to occur in altricial birds (Schew and Ricklefs 1998, Lepczyk and Karasov 2000; but see Remes and Martin 2002, Bize et al. 2006). In one study, addition of body mass and growth rates in overfed young in the laboratory did not differ from that of wild young Introduction Introduction 2 A Guide to Nestling Development and Aging in Altricial Passerines (Konarzewski et al.1996). These results indicate that young may be growing at the maximum rate allowed by cell function and physiology. Analyzing Growth An important part of visualizing and analyzing nestling growth is the use of fitted growth equations (Ricklefs 1967, 1983). When fitted into a growth equation, using non-linear regression, three components of growth are provided: the rate, magnitude, and form of growth. When graphed, nestling growth is often shown to increase, reach a peak, and finally level off in a sigmoidal shape. These equations simplify and allow for comparative analysis of growth between and within species. Information on adult body weight and size are also an important aspect of analyzing growth with these equations (O’Connor 1984); adult body size measurements are provided for the study species in this guide (Appendix A). Alternatively, growth data can also be used to build predictive models of age (Holcomb and Twiest 1971, Hamel 1974). Growth Patterns and Aging Inherent species specific patterns of growth and development can often be used to age nestlings (Starck and Ricklefs 1998a). In nestling growth patterns, each body component can begin growth at a different point in time relative to other components, resulting in a staggered growth pattern. Specific patterns in this type of growth are generally adaptations for nest survival. For example, in some species, contour feathers tend to rapidly grow and unsheathe before the remiges, providing important insulation cover early in life, when young cannot self-thermoregulate (Murphy 1981). In another example, growth of the tarsus or gape, important for food acquisition, may proceed rapidly during the early nestling stage (O’Connor 1984). Besides growth, developmental events (e.g., pin-feather eruption patterns, eye opening, and behavior) can be age specific and are readily observed (Ricklefs 1966, Murphy 1981). Thus, using a combination of several growth measurements can provide reliable aging throughout the nestling period (King and Hubbard 1981, Murphy 1981, Haggerty 1994, Podlesak and Blem 2002). Aging Recommendations The type and number of measurements needed for reliable aging may vary among species but preliminary analysis of our data shows that wing length, tarsus length, weight, and culmen provide good predictive models of age. Since nestlings may be growing at a maximized rate, age estimates can be informed by considering the development of the most advanced nestlings, and by using more than one nestling. In nests parasitized by Brown-headed Cowbird (Molothrus ater), where all the young may be receiving less food than normal, aging host young may or may not be reliable (Kilner et al. 2004, Weatherhead 1989). Aging of the Brown-headed Cowbird young may be possible, depending on the host species (Scott 1979, Kilpatric 2002). With any aging technique, it is important to be aware that deviations from normal growth and development can occur, preventing accurate predictions of age for those individuals. Data from known age nests can bring attention to abnormal developmental patterns and rates in the local populations. Measuring nestlings on more than one day can also reveal deviations from normal development. Energy restrictions can be a source of another type of staggered growth where nestlings are forced to allocate resources to areas of development more important to their survival (Oyan and Anker-Nilssen 1996, Dahdul and Horn 2003). This could result in some body components growing normally, while others slow or stop growing completely (Boag 1987, Lepczyk and Karasov 2000). Feather developmental events in particular, such as pin feather eruption, may proceed normally, despite abnormal growth in other body components (Schew and Ricklefs 1998). Hence, though measuring several variables may help reduce aging error, if any abnormal patterns are identified individuals should be aged with caution. Variables Used for Aging Several measurements of growth have been widely used in the literature. We have attempted to be as inclusive as possible with the variables used in this guide. Given the time restrictions of measuring young, we have narrowed the variables to those that proved useful in the literature and in field trials. Individual feather tracts.––The developmental timing of feather tracts tends to follow a consistent age related pattern within a species and are the most easily noted traits when examining nestlings. The flight feathers will often begin to emerge and develop in pin before the contour feathers; however, contour feathers will often begin to unsheathe before the flight feathers (Murphy 1981). Feather development may proceed independently of growth in body size or mass gain (Ricklefs 1968a). These qualities make feather development an important component of aging nestlings. Wing Chord.––Wing chord is another simple measurement that is reported often in the literature. As part of staggered development, wing growth can proceed quickly throughout the nestling stage and has been shown to provide a good estimate of age (Ricklefs 1975, Haggerty 1994, McCarty 2001). Weight.––Data on mass gain is the most common data published on nestling growth. This may be, in part, because it is a relatively easy measurement to take. Though nestlings may gain mass at rapid levels, mass gain may be more sensitive than other parameters to food availability or environmental stress and may not always reflect the maturity level of a nestling (Boag 1987, Lepczyk and Karasov 2000). In some species, such as aerial foragers and cavity nesters, mass may even reach an asymptotic peak above normal adult weight, and then diminish to normal levels before fledging (Ricklefs 1968b). For these reasons, mass should not be used alone to 3 indicate age. Nevertheless, its wide availability in the literature makes mass a practical component of nestling aging. Tarsus.––Tarsus length may grow normally even with food restrictions (Best 1977, Lepczyk and Karasov 2000). The tarsus is also a part of the staggered development seen in nestlings. For example, in the Bachman’s Sparrow (Aimophila aestivalis), the tarsus was shown to grow quickly during the early part of the nestling stage before tapering off after day 5 (Haggerty 1994). Primary and rectrix pin lengths.––Flight feather growth proceeds quickly and may be affected by factors different from those that affect mass gain (Murphy 1985). Also, growth of the remiges may not be as erratic as weight gain, making it a more-reliable age indicator (King and Hubbard 1981, Boag 1987). While primary pins usually grow rapidly, in some species this growth may begin to slow down and in some cases length may reach a maximum late in the nestling period. Rectrices, on the other hand, usually do not begin to develop until the latter half of the nestling period, where they proceed to grow rapidly. This division in growth schedule allows one to measure rapidly growing flight feathers throughout the nestling stage. Culmen.––The culmen can serve as a good age indicator since it may grow normally despite food restrictions (Lepczyk and Karasov 2000). For many species, the culmen is also a relatively simple measurement to take. Eyes.––Nestlings will often begin to open their eyes at a predictable age. Thus, this event can serve to reinforce age estimates. The date the eyes begin to open is especially useful, while the degree of eye opening can vary considerably. Longest broken primary.––The degree of exposed primary feather is a development process that may proceed independent of growth and can be used to reinforce nestling age estimates. Total length.––Total length is historically an important standard measurement (Baldwin et al. 1931) that is relatively simple and quick to take. However, the length can increase quickly, and should be used with caution. The position of the young can reduce or increase this measurement dramatically. Gape and rictus.––The gape can grow quickly early in the nestling period. However, the rictus (soft tissue at base of bill) is very pliable during growth, and measurements of the gape can increase or decrease greatly between days as the rictus contracts and expands. Hence, it should be both measured and used with caution. Physical and behavioral descriptors.––Because certain behavioral events can consistently occur at a specific age and are easily noted (Ricklefs 1966), they are an important part of aging the young. They can also prove useful in narrowing age determination when growth data places the age of the nestling within a certain range. Yellow-breasted chat (Icteria virens). Chris McCreedy/PRBO Introduction 4 A Guide to Nestling Development and Aging in Altricial Passerines We had two primary objectives in writing this guide, to report and promote research on species specific patterns of altricial passerine nestling development and aging, and to achieve better estimates of nestling ages. We present nestling data on seven species of altricial passerines: Dusky Flycatcher (Empidonax oberholseri), Carolina Wren (Thryothorus ludovicianus), Wrentit (Chamea fasciata), Sprague’s Pipit (Anthus spragueii), Song Sparrow (Melospiza melodia), Chestnut-collared Longspur (Calcarius ornatus), and American Goldfinch (Cardeulis tristis). In addition, nestling data collection techniques have been highly variable, limiting the potential for data sharing, limiting comparisons across species and families, and limiting the use of data in combined analyses. Therefore, we present suggestions for standardizing the collection of nestling data in Appendix B. Objectives 5 Using the Species Accounts In the species accounts we report detailed information on species-specific nestling development. A primary goal in the design of the accounts was to make them as useful as possible for those interested in aging nestlings. The first page of each account begins with life history information for the particular species. This is followed immediately by tables listing distinguishing developmental criteria (i.e., appearance) and general feather development patterns throughout the nestling period. On subsequent pages, averages and ranges of morphometric data and more-detailed descriptions of development are presented on a day-by- day basis. Within the tables, we have attempted to list morphometric data in descending order of utility. Priority is given to characteristics with a fast growth rate, high ease and accuracy of measuring, and prominence in the literature. Priority was also given to those characteristics that proved useful for aging via field trials, preliminary analysis, and through prior experience aging altricial nestlings. For comparative purposes, the variables are listed in the same order for each day and species. We recommend a systematic approach when using the tables for aging nestlings, beginning with an initial filtering of possible age ranges using the information on the first page of each species account. These age ranges can then be further refined through the use of the daily descriptions. Measurements and Terminology It is important that measurements are taken in a standard format, using terminology that is consistent. The variables described below were taken for each species in this guide and are presented in the account tables. For several of the measurements used, we followed guidelines as described by Pyle (1997) or Baldwin et al. (1931). Measurements taken with electronic calipers are to the nearest 0.01 mm and measurements taken with a ruler are to the nearest 0.5 mm. Weight was measured with an electronic scale to the nearest 0.1 g. A full treatment on the methods used to collect this data is provided in Appendix B. Feather definitions: Apteria: The naked spaces found between the feather tracts. Contour feathers: The feathers of the head, body, and coverts excluding any remiges or rectrices. Eruption: The breaking down of the pin sheath usually occurring at the distal tip of the pin, exposing the feather. Neossoptiles: Down feathers present when a bird hatches. Pterylae: Areas on the skin from which feathers grow; the feather tracts. Papillae: A small projection of tissue usually used to describe feathers at an early stage of development prior to emergence from the skin. Methods Methods Fig. 1. Dorsal and ventral views of a nestling with the individual feather tracts marked and identified. 6 A Guide to Nestling Development and Aging in Altricial Passerines Fig. 2. Tarsus with measurement indicators at the tibiotarsus joint and distal end of the last leg scale. Remiges: The flight feathers of the wing, including the primaries, secondaries, and tertials. Rectrices: The flight feathers of the tail. Teleoptiles: All flight and contour feathers found on a bird. Weight. –– Weight is taken by placing the bird directly on the scale (older chicks may need to be placed in a container). To reduce differences, this should be the last measurement taken so the nestling can defecate before weight is recorded. Tarsus.—Tarsus is measured with calipers from the tibiotarsus joint to the distal end of the last leg scale before the toes emerge (Fig. 2). When it is difficult to see the end of the tibiotarsus joint, feel for it with fingertips; likewise, to find the last leg scale before the toes emerge, bend the foot and place one end of the calipers at the bend, checking that the bend is indeed at the distal end of the last leg scale. It may help to become familiar with the number of scales present on the ankle before the toes emerge. This helps because identifying the last leg scale can sometimes be difficult, especially in younger birds. Wing chord.––Early in development, the wing is measured with a wing ruler from the bend of the wrist to tip of the distal segment of the forelimb. Once the primary pins have emerged, wing chord is measured with a wing ruler, unflattened, from the bend of the wrist to the tip of the primaries (Fig. 3). Fig. 3. Wing chord as measured with a wing ruler, without flattening or pressing down on the wing. Primary and rectrix pin lengths.––Pin lengths are measured with a ruler from the point of emergence from the skin to the end of the feather or pin (Fig. 4). Fig. 4. Pin lengths as measured from the point of emergence from the skin. Culmen.––Culmen is measured with calipers from the anterior end of the nostrils to the tip of the bill (Fig. 5). For practical reasons, the culmen in some species may need to be measured differently. Exposed culmen is an alternate measurement taken for some species and is measured along the ridge of the upper mandible from the tip of the feathers at the base of the bill to the bill tip. If you are uncertain about how to measure the bill in a species, you should consult the literature (Pyle 1997). Fig. 5. The culmen as measured from nares to tip. Eyes.––Eyes are described as closed, partially open when the eyelids begin to open, or fully open when they appear fully alert and exposed. Total length.––Total length is a measure of body size and is taken from the tip of bill to the tip of the tail bud with the bird placed on its back along a ruler (Fig. 6). For consistency, the chick should be in a relaxed and natural position with its body and neck gently stretched out so that its bill is almost parallel with the ruler. Fig. 6. Total length taken from the tip of the bill to the tail bud. Longest broken primary.––The longest exposed primary (exposed feather portion only) is measured with a ruler from the point of emergence from the pin shaft to the distal tip of the feather itself (Fig. 7). Fig. 7. The exposed portion of the longest broken primary as measured with a ruler. Gape and rictus.––The gape (mouth opening) is measured with calipers at its widest length (Fig. 8). The pliable tissue (rictus) at base of the bill Results 7 should not be bent or squeezed by the calipers during measurement of the gape. The gape can grow quickly early in the nestling period and measurements can increase or decrease greatly between days as the rictal tissue contracts and expands. Hence, the gape should be both measured and used with caution. Fig. 8. The gape as measured with calipers. Physical and behavioral descriptors.––Examples of behavioral data include movement and begging behavior, opening of eyes, call notes, shivering, and reaction to the observer. We describe appendage movement abilities and begging behavior as very slow and weak, periodic; slow and weak, but steady; quick and uncontrolled, frequent; or quick and deliberate. Any sounds, skin or bill color, and notable changes in appearance are also described. Species Account Tables Species information.—Species accounts start with nest-period information, important to aging nests found before hatching. Nest-period information includes means and ranges in clutch size, nest building time, incubation period, and nestling period. These parameters may vary temporally and spatially and are more accurate when calculated from your specific population (versus from the literature). Indicator table.––This table provides an “at a glance” reference to prominent developmental events and their approximate day of appearance. Included are events that were found to be reliable for aging within one or two days and/or were easy to note visually. This table should be used together with the feather development table. The daily accounts can be consulted for more detail. General feather development.––This table provides a quick reference to prominent feather development events and their approximate day of appearance. The general progression of feather development is shown to guide users to the approximate age range of nestlings. A range of possible ages should be selected using this table together with the indicator table described above. The daily accounts can then be consulted for more detail. Key visual indicators.—List of visual descriptors we found to be prominent and reliable for each day that can serve to reinforce age estimates. Examples of descriptors include behavior, general appearance, color changes, etc. Typical dates for banding are noted here as are cautions regarding premature fledging (“jumping”). Photographs.––A representative photograph is presented for each day. These photos can be used by field biologists to become familiar with the general appearance of the nestlings, including the appearance of key visual indicators and feather tracts. Feather tract data.––The percentage of individuals at a given developmental stage for each feather tract is presented. Feather development events are indicated respectively as “Not Visible - N”, “Visible - V” (below skin), “Pin - P” (above and broken through skin), “Unsheathing - U” (feather partially exposed), or “Fully Unsheathed - F” for each individual tract (Fig. 9). The most advanced stage of a given feather tract is indicated. For example, a tract with exposed pins of which only a few are unsheathing is marked as U for unsheathing. Feather tracts are listed in the same order each day for ease of comparison across days. Tracts are listed beginning with the capital tract, then continuing posteriorly and ending with the ventral tract. The sample size in individuals is provided for each feather tract. Pin (above and broken through skin) Visible (below skin) Unsheathing (feather partially exposed) Fig. 9. Example of feather development and appearance, using a Wrentit on Day 7. Morphometric data.––Growth data (mean, standard deviation, and range) are presented for several measurements to provide indices of body size for each day. The sample unit is the number of nestlings measured. General description.––A more complete description of the appearance of feather tracts and behavioral characteristics is given for each day of nestling development. 8 A Guide to Nestling Development and Aging in Altricial Passerines Species Accounts Dusky Flycatcher Empidonax oberholseri Data collection: Lassen National Forest, Tehama County, California. Nests: n = 9 (2004) Nest Period Data: No data Building: No data Clutch size: No data Incubation period: No data Nestling period: No data Indicator Table: Dusky Flycatcher visual characteristics typical at a given age. No pins are visible 1 Alar pins in a band centered across wing 2 Alar pins have grown towards posterior edge of wing 3 Alar pins have grown to the wing edge and may be pushing out on skin 4 Alar pins have emerged 4-5 Eyes begin to open 5-6 Dorsal and ventral tracts begin to unsheathe 7 All feather tracts begin to unsheathe 8 Primary pins begin to unsheathe 9 Young appear feathered due to extensive unsheathing 10 Contrasting buffy wing bars are readily visible 10-11 Contour feather pins are not visible due to extensive unsheathing 12 Indicator characteristics Age Indicator characteristics Age General Feather Development: Dusky Flycatcher feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N N N N V N N N N 2 N N N N V N N N N V 3 N V N V N V V N V N N V N V 4 V P V P V P V P V P N V V P V P 5 V P P V P V P V P V P V P V P 6 P P U P U P V P V P V P P U 7 P P U P U P U P U P U P U P U 8 U U U U U U U U 9 U U U U U U U U 10 U U U U U U U U 11 U U U U U U U U 12 U U U U U U U U Results Results 9 Day 1 Key Visual Indicators: - No pins are visible - Down may be matted - Young are small (egg size) Feather Tract Development Tract N V P U F n Capital 100 12 Dorsal 100 12 Humeral 100 12 Alar 84 16 12 Femoral 100 12 Crural 100 12 Caudal 100 12 Ventral 100 12 Morphometric Data Measurements Mean ± SD Min Max n Weight 1.475 ± 0.325 1.0 2.0 12 Tarsus 5.03 ± 0.486 4.5 5.8 12 Wing Chord 5.8 ± 0.411 5.3 6.5 12 Culmen 1.85 ± 0.392 1.4 2.5 12 Outer Primary 0 0 0 12 Outer Rectrix 0 0 0 12 Longest Broken Primary 0 0 0 12 Length 30.58 ± 2.392 28.0 35.0 12 Gape 6.74 ± 1.750 1.8 9.0 12 General Description Eyes closed. Young are egg size. No pins are visible below skin. Down may be moist and matted down and is present on the capital, humeral, dorsal, alar, crural, and ventral tracts. Bill is orange-yellow. Dusky Flycatcher (Empidonax oberholseri) continued Day 2 Key Visual Indicators: - Subcutaneous alar pins just visible and centered along dorsal surface of wing Feather Tract Development Tract N V P U F n Capital 100 6 Dorsal 100 6 Humeral 100 6 Alar 33 67 6 Femoral 100 6 Crural 100 6 Caudal 100 6 Ventral 83 17 6 Morphometric Data Measurements Mean ± SD Min Max n Weight 1.95 ± 0.243 1.6 2.3 6 Tarsus 6.02 ± 0.585 5.5 7.1 6 Wing Chord 6.73 ± 0.787 5.8 7.8 6 Culmen 1.88 ± 0.214 1.5 2.1 6 Outer Primary 0 0 0 6 Outer Rectrix 0 0 0 6 Longest Broken Primary 0 0 0 6 Length 31.5 ± 1.643 28.0 35.0 6 Gape 7.2 ± 0.642 6.2 7.9 6 General Description Eyes closed. Alar pins are becoming visible, are individually distinguishable, and are centered along the dorsal surface of the wing. Ventral pins may just be visible. No other pins are visible. 10 A Guide to Nestling Development and Aging in Altricial Passerines Day 3 Key Visual Indicators: - Alar pins have grown towards posterior edge of wing - All tracts may be visible except for crural tract - No pins have emerged Feather Tract Development Tract N V P U F n Capital 33 67 12 Dorsal 8 92 12 Humeral 8 92 12 Alar 100 12 Femoral 33 67 12 Crural 100 12 Caudal 33 67 12 Ventral 17 83 12 Morphometric Data Measurements Mean ± SD Min Max n Weight 3.14 ± 0.626 2.1 4.1 12 Tarsus 6.28 ± 0.697 5.3 7.8 12 Wing Chord 7.46 ± 1.141 5.6 6.5 12 Culmen 2.21 ± 0.408 1.5 2.5 12 Outer Primary 0 0 0 12 Outer Rectrix 0 0 0 12 Longest Broken Primary 0 0 0 12 Length 35.75 ± 3.86 31.0 43.0 12 Gape 8.55 ± 0.843 6.6 9.5 12 General Description Eyes closed. Capital tract may be visible as a few gray flecks. Dorsal tract visible as a light-gray stripe along the spine. Humeral tract visible as a short gray band. Alar pins have grown towards the posterior edge of wing. Femoral tract may appear as a few individual gray flecks. Crural tract is not visible. Caudal tract may appear as a thin light-gray band. Ventral tract is visible below skin. Dusky Flycatcher (Empidonax oberholseri) continued Day 4 Key Visual Indicators: - Alar pins have grown to the posterior edge of wing and may be pushing out on skin - Young appear dark overall due to darkening and lengthening of subcutaneous pins Feather Tract Development Tract N V P U F n Capital 62.5 37.5 8 Dorsal 62.5 37.5 8 Humeral 50 50 8 Alar 62.5 37.5 8 Femoral 88 12 8 Crural 37.5 62.5 8 Caudal 88 12 8 Ventral 50 50 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 4.01 ± 0.574 3.2 5.0 10 Tarsus 8.59 ± 1.099 7.1 10.3 10 Wing Chord 9.55 ± 0.927 8.5 11.1 8 Culmen 2.49 ± 0.335 2.0 3.0 10 Outer Primary 0.1 ± 0.316 0 1.0 10 Outer Rectrix 0 0 0 10 Longest Broken Primary 0 0 0 10 Length 39.6 ± 3.098 35.0 44.0 10 Gape 9.24 ± 0.599 8.0 10.0 10 General Description Eyes closed. Capital, dorsal, and humeral tracts have darkened and may be pressing up on skin surface. Alar pins have grown to the wing edge and may be pushing out on skin. Femoral pins have darkened and lengthened. Crural tract just becoming visible. Caudal tract is visible as a thin dark-gray band. Ventral pins may be pressing up on skin or some may be just emerging. Results 11 Day 5 Key Visual Indicators: - Alar pins have typically emerged - Contour feather tracts beginning to emerge, just above skin surface Feather Tract Development Tract N V P U F n Capital 25 75 8 Dorsal 12.5 87.5 8 Humeral 25 75 8 Alar 14 86 7 Femoral 25 75 8 Crural 37.5 62.5 8 Caudal 62.5 37.5 8 Ventral 12.5 87.5 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 4.91 ± 0.926 3.5 6.3 8 Tarsus 8.93 ± 0.991 7.4 10.1 8 Wing Chord 10.51 ± 3.064 3.8 13.4 8 Culmen 2.58 ± 0.324 2.1 3.2 8 Outer Primary 0.56 ± 0.678 0 2.0 8 Outer Rectrix 0 0 0 8 Longest Broken Primary 0 0 0 8 Length 43.25 ± 3.732 40.0 50.0 8 Gape 9.9 ± 0.321 9.5 10.6 8 General Description Some individuals may begin to open their eyes. Bill is becoming gray at the tip. Capital pins just beginning to emerge. Dorsal and humeral tracts typically emerging. Alar primary and secondary pins have emerged. Femoral and crural tracts have lengthened and tips may be just out. Caudal tract band has lengthened. Most ventral pins have emerged. Dusky Flycatcher (Empidonax oberholseri) continued Day 6 Key Visual Indicators: - Eyes typically opening - All tracts have typically emerged - Outer primary pins measure about 2mm in length Feather Tract Development Tract N V P U F n Capital 100 12 Dorsal 83 17 12 Humeral 25 75 8 Alar 100 12 Femoral 8 92 12 Crural 27 73 11 Caudal 27 73 11 Ventral 83 17 11 Morphometric Data Measurements Mean ± SD Min Max n Weight 6.34 ± 0.981 4.4 8.3 12 Tarsus 11.03 ± 0.945 9.5 12.6 12 Wing Chord 13.15 ± 2.166 8.7 16.3 12 Culmen 2.83 ± 0.391 2.3 3.5 12 Outer Primary 2.13 ± 1.494 0.5 4.0 12 Outer Rectrix 0.13 ± 0.311 0 1.0 12 Longest Broken Primary 0 0 0 12 Length 43.83 ± 2.368 40.0 47.0 12 Gape 10.63 ± 0.502 9.9 11.5 12 General Description Eyes typically beginning to open. Most capital tract pins have emerged. Most dorsal pins have emerged and may show light tips. Alar pins have emerged, including some coverts. Primaries and secondaries may show light tips. Several femoral and crural pins have emerged. 12 A Guide to Nestling Development and Aging in Altricial Passerines Day 7 Key Visual Indicators: - Dorsal and ventral tracts typically unsheathing - Some alar tract coverts may be beginning to un-sheathe Feather Tract Development Tract N V P U F n Capital 100 3 Dorsal 33 67 3 Humeral 67 33 3 Alar 67 33 3 Femoral 67 33 3 Crural 67 33 3 Caudal 67 33 3 Ventral 33 67 3 Morphometric Data Measurements Mean ± SD Min Max n Weight 8.33 ± 0.635 7.6 8.7 3 Tarsus 12.43 ± 1.00 11.4 13.4 3 Wing Chord 18.67 ± 1.963 16.4 19.8 3 Culmen 2.97 ± 0.115 2.9 3.1 3 Outer Primary 4.33 ± 0.577 4.0 5.0 3 Outer Rectrix 1.0 ± 0.0 1.0 1.0 3 Longest Broken Primary 0 0 0 3 Length 55.33 ± 2.887 50.0 55.0 3 Gape 11.4 ± 0.458 11.0 11.9 3 General Description Capital tract pins have lengthened and are still typically in pin. Dorsal pins have lengthened and some are beginning to unsheathe. All humeral pins have emerged and may begin to unsheathe. Alar pins have lengthened and coverts may be unsheathing. Some femoral and crural tracts may show white tips or have begun to unsheathe. Rectrices have begun to emerge. Ventral tract is typically unsheathing. Young grasp uncontrollably. Bill is becoming a purplish pink with a gray tip. Dusky Flycatcher (Empidonax oberholseri) continued Day 8 Key Visual Indicators: - All contour feather tracts typically unsheathing - Some secondaries beginning to unsheathe Feather Tract Development Tract N V P U F n Capital 100 4 Dorsal 100 4 Humeral 100 4 Alar 100 4 Femoral 100 4 Crural 100 4 Caudal 100 4 Ventral 100 4 Morphometric Data Measurements Mean ± SD Min Max n Weight 8.81 ± 1.143 6.5 10.4 8 Tarsus 13.18 ± 1.051 11.6 14.5 8 Wing Chord 20.18 ± 4.713 10.1 24.0 8 Culmen 3.51 ± 0.372 3.2 4.3 8 Outer Primary 6.5 ± 2.074 4.0 9.0 6 Outer Rectrix 2.17 ± 1.169 1.0 4.0 6 Longest Broken Primary 0.38 ± 0.744 0 2.0 8 Length 51.0 ± 2.878 46.0 55.0 8 Gape 11.6 ± 0.875 10.1 12.8 8 General Description Capital tract pins have typically begun to unsheathe. Some secondaries are beginning to unsheathe. Primaries are showing white tips or just beginning to unsheathe. Most pins of all contour feathers have begun to unsheathe. Bill continues to darken and anteriorly gray. Young can move and grasp constantly. Results 13 Day 9 Key Visual Indicators: - Primary tips beginning to unsheathe Feather Tract Development Tract N V P U F n Capital 25 75 8 Dorsal 100 8 Humeral 100 8 Alar 100 8 Femoral 100 8 Crural 25 75 8 Caudal 12.5 87.5 8 Ventral 100 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 9.075 ± 0.918 7.0 9.8 8 Tarsus 14.13 ± 1.412 11.4 16.2 8 Wing Chord 22.8 ± 2.370 19.8 25.8 8 Culmen 3.39 ± 0.426 2.6 3.9 8 Outer Primary 7.5 ± 2.204 4.0 10.0 8 Outer Rectrix 2.88 ± 1.246 1.0 5.0 8 Longest Broken Primary 0.88 ± 1.126 0 3.0 8 Length 53.38 ± 4.069 46.0 60.0 8 Gape 11.38 ± 0.373 11.1 12.0 8 General Description All feather tracts are clearly unsheathing, although sheaths may still be prominent on capital and dorsal tracts. Primary pins are beginning to unsheathe and most alar feathers are mostly in their sheath. Young are able to hop around, though are not well coordinated. May give contact “pip” calls. Dusky Flycatcher (Empidonax oberholseri) continued Day 10 Key Visual Indicators: - Most alar pins have begun to unsheathe - Young appear soft due to extent of unsheathing - Young appear alert Feather Tract Development Tract N V P U F n Capital 100 8 Dorsal 100 8 Humeral 100 7 Alar 100 8 Femoral 100 8 Crural 100 8 Caudal 100 8 Ventral 100 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 10.43 ± 1.132 8.3 11.9 8 Tarsus 14.69 ± 0.872 13.3 16.2 8 Wing Chord 28.95 ± 2.432 24.1 32.0 8 Culmen 3.89 ± 0.259 3.5 4.2 8 Outer Primary 12.5 ± 2.507 8.0 15.0 8 Outer Rectrix 5.13 ± 1.356 3.0 7.0 8 Longest Broken Primary 3.5 ± 1.927 1.0 6.0 8 Length 55.75 ± 3.770 50.0 61.0 8 Gape 11.7 ± 0.623 11.0 12.9 8 General Description All tracts continue to unsheathe and pin sheaths are mostly hidden by exposed feathers. Several primaries and secondaries are now unsheathed about 3-4 mm. Bill has turned about 75% gray. Young are alert and can hop. 14 A Guide to Nestling Development and Aging in Altricial Passerines Day 11 Key Visual Indicators: - Contrasting buffy wing bars are visible - Young are very alert and can hop readily on the ground Feather Tract Development Tract N V P U F n Capital 100 6 Dorsal 100 6 Humeral 100 6 Alar 100 6 Femoral 100 6 Crural 100 6 Caudal 100 6 Ventral 100 6 Morphometric Data Measurements Mean ± SD Min Max n Weight 10.3 ± 0.346 10.0 10.6 4 Tarsus 15.52 ± 1.134 13.5 16.5 6 Wing Chord 31.8 ± 3.295 27.8 35.5 6 Culmen 3.93 ± 0.398 3.4 4.4 6 Outer Primary 14.0 ± 3.033 9.0 17.0 6 Outer Rectrix 6.77 ± 2.002 3.0 9.0 6 Longest Broken Primary 6.67 ± 2.582 3.0 9.0 6 Length 55.5 ± 4.324 50.0 60.0 6 Gape 11.97 ± 0.294 11.6 12.4 6 General Description All feather tracts continue to unsheathe extensively. Primaries are unsheathed about 6-7mm. Contrasting buffy wing bars are clearly visible along the wing coverts. Bill has darkened almost entirely except for the gape. Nestlings are prone to “jump” on this day. Use caution. Dusky Flycatcher (Empidonax oberholseri) continued Day 12 Key Visual Indicators: - Contour feather pins are obscured due to extensive unsheathing - May appear similar to Day 11 Feather Tract Development Tract N V P U F n Capital 100 7 Dorsal 100 7 Humeral 100 7 Alar 100 7 Femoral 100 7 Crural 100 7 Caudal 100 7 Ventral 100 7 Morphometric Data Measurements Mean ± SD Min Max n Weight 11.22 ± 1.030 9.2 12.1 6 Tarsus 16.03 ± 0.325 15.5 16.4 7 Wing Chord 37.8 ± 2.204 34.1 40.5 7 Culmen 4.24 ± 0.416 3.5 4.8 7 Outer Primary 17.57 ± 1.134 16.0 19.0 7 Outer Rectrix 11.0 ± 1.155 9.0 12.0 7 Longest Broken Primary 11.0 ± 6.880 1.0 17.0 7 Length 62.29 ± 2.360 59.0 66.0 7 Gape 12.2 ± 0.455 11.7 13.1 7 General Description Nestlings appear very similar to Day 11. Wing chord and longest broken primary have substantially increased in length. Contour feather pins are obscured by unsheathed feathers. Nestlings should not be handled if they appear prone to jump from the nest. Results 15 Species Accounts Carolina Wren Thryothorus ludovicianus ludovicianus Data collection location: Tennessee Valley Authority Reservation, Muscle Shoals, Colbert County, Alabama Nests: n = 3 (2001), n = 2 (2002), n = 16 (2004) Nest Period Data (Haggerty and Morton 1995): Average (range), n = number of nests Building: no data Clutch size: 4.3 (3 -- 6) eggs, n = 88 Incubation: 14.8 (12 - 16) days, n = 16 Nestling: 12.2 (10 - 16) days, n = 5 Indicator Table: Carolina Wren visual characteristics typical at a given age. Alar pins in a band centered across wing 1 Down is matted or moist 1 Alar pins stretched towards posterior edge 2 Primaries and secondaries just emerged 3 Pins of humeral, dorsal, and capital tracts appear ready to emerge 4 Eyes begin to open 4-5 Alar pin tips appear pale, ready to unsheathe 6 Alar pins begin to unsheathe 7 Pins of most tracts appear ready to unsheathe 7 Contour tracts except capital begin to unsheathe 8 All feather tracts clearly unsheathing 9 Indicator characteristics Age Indicator characteristics Age General Feather Development: Carolina Wren feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N N N V V N N N N 2 N V N V N V V P N N N V N V 3 N V N V N V V P N V N V N V N V 4 V V V P P N V N V N V N V 5 V P V P V P P V P V P V P V P 6 V P V P V P P U V P V P V P V P U 7 V P U P U P U P U P U P U P U P U 8 P U P U P U U P U P U P U U 9 P U U U U U U U U 10 U U U U U U U U 16 A Guide to Nestling Development and Aging in Altricial Passerines Day 1 Key Visual Indicators: - Subcutaneous alar pins are centered along the dor-sal wing surface - Most other feather tracts are not visible below skin - Down is often matted and moist, young are egg size. Feather Tract Development Tract N V P U F n Capital 100 35 Dorsal 100 36 Humeral 97 3 36 Alar 100 36 Femoral 100 36 Crural 100 35 Caudal 100 36 Ventral 100 36 Morphometric Data Measurements Mean ± SD Min Max n Weight 2.24 ± 0.398 1.6 3.25 36 Tarsus 6.69 ± 0.475 5.6 7.9 36 Wing Chord 6.29 ± 0.541 4.4 7.6 36 Culmen 2.05 ± 0.210 1.6 2.4 36 Outer Primary 0 0 0 26 Outer Rectrix 0 0 0 34 Longest Broken Primary 0 0 0 26 Length 35.5 ± 2.302 32.0 40.0 26 Gape 8.34 ± 0.696 7.1 9.8 24 General Description Eyes closed and lids appear dark. Bill pale, except for dark tip; rictus cream yellow to spectrum yellow at corners. Skin is reddish-pink. Grayish-brown down on capital, humeral and spinal tracts; often matted. Distinct, dark primary and secondary pin feathers visible below skin in alar tract; pins still very small and centered across dorsal surface of wings. No pigmented pins usually visible below skin in other tracts. Moves limbs and head very slowly. Soft “pep” calls heard. Often remains in curled, embryo-like position with head resting on large protruding abdomen. Carolina Wren (Thryothorus ludovicianus ludovicianus) continued Day 2 Key Visual Indicators: - Alar pins stretched to posterior edge of wing Feather Tract Development Tract N V P U F n Capital 88 12 26 Dorsal 52 48 27 Humeral 52 48 27 Alar 70 30 27 Femoral 100 27 Crural 100 26 Caudal 93 7 27 Ventral 96 4 27 Morphometric Data Measurements Mean ± SD Min Max n Weight 3.13 ± 0.417 2.4 4.0 27 Tarsus 7.67 ± 0.444 6.6 8.7 27 Wing Chord 7.12 ± 0.459 6.4 8.4 27 Culmen 2.35 ± 0.197 2.0 2.8 27 Outer Primary 0 0 0 21 Outer Rectrix 0 0 0 26 Longest Broken Primary 0 0 0 21 Length 39.5 ± 2.524 36.0 45.0 20 Gape 9.51 ± 0.485 8.6 10.2 19 General Description Eyes closed. Humeral and dorsal tracts may have very small, dark pigmented pins below skin; appear as small dark dots. Alar pins under skin larger and merge to give arm, especially hand, a dark color; no flesh-colored stripe visible along posterior edge of dorsal surface of arm. Pigmented pins usually not visible under skin in other tracts. Skin more flesh colored, less reddish than day 1. Down fluffy, not matted. Slowly lifts head and begs; often remains in curled up position. Results 17 Day 3 Key Visual Indicators: - Primaries and some secondaries emerged - Longest primary usually <1mm Feather Tract Development Tract N V P U F n Capital 6 97 33 Dorsal 6 94 33 Humeral 3 97 33 Alar 6 97 33 Femoral 76 24 33 Crural 30 70 33 Caudal 21 79 33 Ventral 55 45 33 Morphometric Data Measurements Mean ± SD Min Max n Weight 4.70 ± 0.806 3.3 6.7 33 Tarsus 9.16 ± 0.764 7.9 11.0 33 Wing Chord 8.95 ± 0.847 7.8 12.0 33 Culmen 2.66 ± 0.212 2.3 3.0 33 Outer Primary 0.60 ± 0.400 0 2.0 26 Outer Rectrix 0 0 0 31 Longest Broken Primary 0 0 0 27 Length 44.04 ± 3.130 36.0 50.0 26 Gape 10.46 ± 0.638 9.5 12.1 25 General Description Eyes closed. Pins of alar tract clearly emerged. Pale tissue bands may be present in ventral tract and femoral tract. Subcutaneous pigmented pins in femoral tract may be visible as small flecks. Dark subcutaneous pins clearly visible in spinal, humeral and capital tracts. Longest primary pin (P7) usually 1 mm or less. Caudal tract visible as subcutaneous gray color and emerged hair-like pin tips may be visible. Crural tract may have very small pigmented subcutaneous pins. Upper bill brownish. Movements more frequent and strong. Carolina Wren (Thryothorus ludovicianus ludovicianus) continued Day 4 Key Visual Indicators: - Pins of humeral, dorsal, and capital tracts appear ready to emerge - Longest primary usually between 1 - 2mm - Pigmented pins becoming visible on ventral tract near chest and axilla Feather Tract Development Tract N V P U F n Capital 100 24 Dorsal 100 25 Humeral 96 4 25 Alar 100 25 Femoral 32 68 25 Crural 8 92 24 Caudal 4 96 25 Ventral 24 76 25 Morphometric Data Measurements Mean ± SD Min Max n Weight 6.20 ± 1.119 4.2 9.5 25 Tarsus 10.82 ± 1.063 9.0 13.9 25 Wing Chord 11.32 ± 1.386 8.7 15.8 25 Culmen 3.15 ± 0.257 2.7 3.5 25 Outer Primary 1.84 ± 0.846 1.0 4.0 23 Outer Rectrix 0.02 ± 0.10 0 0.5 25 Longest Broken Primary 0 0 0 23 Length 49.70 ± 3.560 42.0 58.0 23 Gape 11.67 ± 0.658 10.5 13.0 23 General Description Eyes partially opened. Longest primary measures between 1 and 2 mm. Dark, subcutaneous pins visible in chest area of ventral tract. Dark subcutaneous pins in capital, femoral, caudal and crural tracts. Subcutaneous pins of spinal and humeral tracts appear ready to emerge through skin. Can move body with kicks and wing flaps. 18 A Guide to Nestling Development and Aging in Altricial Passerines Day 5 Key Visual Indicators: - Pins on most tracts just emerged or appear ready to emerge - All alar pins including coverts have emerged - Eyes typically appear partially to fully open Feather Tract Development Tract N V P U F n Capital 88 12 33 Dorsal 60 40 33 Humeral 55 45 33 Alar 100 33 Femoral 79 18 3 33 Crural 67 33 33 Caudal 70 30 33 Ventral 79 21 33 Morphometric Data Measurements Mean ± SD Min Max n Weight 8.20 ± 1.158 5.9 11.1 33 Tarsus 13.03 ± 0.967 11.4 16.2 33 Wing Chord 15.25 ± 1.860 11.2 20.5 33 Culmen 3.67 ± 0.347 3.0 4.4 33 Outer Primary 4.14 ± 1.757 0 9.0 26 Outer Rectrix 0.10 ± 0.201 0 0.5 31 Longest Broken Primary 0.02 ± 0.096 0 0.5 27 Length 53.19 ± 4.350 43.0 65.0 27 Gape 12.36 ± 0.646 11.2 14.4 25 General Description Eyes open. Ventral, dorsal, femoral, humeral, crural and caudal tracts have emerged pins or pins that appear ready to emerge. Capital pins may emerge in nape region. Bill and skin of face dark, contrasts with yellow rictus. Can move body with kicks and wing flaps. Carolina Wren (Thryothorus ludovicianus ludovicianus) continued Day 6 Key Visual Indicators: - Pins on all tracts have emerged - Tips of primary pins are pale, appear ready to unsheathe Feather Tract Development Tract N V P U F n Capital 33 67 24 Dorsal 16 84 25 Humeral 8 92 25 Alar 92 8 25 Femoral 24 76 25 Crural 29 71 24 Caudal 16 84 25 Ventral 20 72 8 25 Morphometric Data Measurements Mean ± SD Min Max n Weight 9.98 ± 1.484 6.4 13.1 25 Tarsus 15.11 ± 1.021 13.0 18.0 25 Wing Chord 19.18 ± 2.483 14.7 25.6 25 Culmen 4.08 ± 0.437 3.1 4.9 25 Outer Primary 7.64 ± 2.097 4.5 13.0 22 Outer Rectrix 0.33 ± 0.396 0 1.2 24 Longest Broken Primary 0.05 ± 0.147 0 0.5 22 Length 58.13 ± 4.703 47.0 66.0 23 Gape 12.66 ± 0.516 11.6 13.7 23 General Description Eyes open. Pins usually emerged in all tracts. Begs directly at nest entrance. May cower and snap bill (inaudible) when nest is disturbed. Kicks and flaps quickly and can easily turn itself over when placed on back. Tips of alar pins pale and look ready to unsheathe. Face dark and contrasts sharply with yellow rictus. Results 19 Day 7 Key Visual Indicators: - Alar pins beginning to unsheathe - Pins of most tracts have pale tips and appear ready to unsheathe Feather Tract Development Tract N V P U F n Capital 3 94 3 29 Dorsal 80 20 30 Humeral 83 17 30 Alar 50 50 30 Femoral 77 23 30 Crural 90 10 29 Caudal 90 10 30 Ventral 70 30 30 Morphometric Data Measurements Mean ± SD Min Max n Weight 11.90 ± 1.557 7.3 14.9 30 Tarsus 17.07 ± 0.974 13.9 18.6 30 Wing Chord 24.04 ± 2.440 17.5 28.4 30 Culmen 4.46 ± 0.369 3.6 5.2 30 Outer Primary 11.53 ± 2.337 8.0 17.0 20 Outer Rectrix 1.15 ± 0.847 0 4.0 28 Longest Broken Primary 0.38 ± 0.705 0 3.0 20 Length 63.45 ± 4.751 55.0 73.0 20 Gape 12.84 ± 0.661 11.8 14.6 20 General Description Alar pin tips pale and often unsheathing. Ventral, dorsal, humeral, and femoral tracts have pins that look ready to open and unsheathing may begin. Can hold head up off clipboard. Pins of ventral and femoral tracts cinnamon colored. Carolina Wren (Thryothorus ludovicianus ludovicianus) continued Day 8 Key Visual Indicators: - All feather tracts typically unsheathing except capital and caudal - Appears alert and active Feather Tract Development Tract N V P U F n Capital 78 22 23 Dorsal 21 79 24 Humeral 21 79 24 Alar 100 24 Femoral 4 96 24 Crural 48 52 23 Caudal 71 29 24 Ventral 100 24 Morphometric Data Measurements Mean ± SD Min Max n Weight 13.53 ± 1.726 8.4 16.15 24 Tarsus 18.55 ± 1.062 16.0 20.7 24 Wing Chord 28.18 ± 2.645 19.6 33.2 24 Culmen 4.92 ± 0.395 4.2 5.9 24 Outer Primary 14.17 ± 4.222 1.3 21.0 20 Outer Rectrix 2.23 ± 1.280 0 6.0 23 Longest Broken Primary 2.08 ± 1.315 0.5 6.0 19 Length 66.80 ± 6.978 53.0 80.0 20 Gape 13.03 ± 0.608 12.0 14.0 20 General Description All tracts but capital and caudal have pins that are clearly ruptured. Very alert; flaps and kicks vigorously, and usually will not remain still during handling. Eyes typically stay open during handling. Eyes and face black. May give fledgling “chip” locator call. Young are typically ready for banding. 20 A Guide to Nestling Development and Aging in Altricial Passerines Day 9 Key Visual Indicators: - All feather tracts clearly unsheathed - Light brown feathers of ventral tract form two broad stripes - Rust colored dorsal feathers form strip on back Feather Tract Development Tract N V P U F n Capital 9 91 22 Dorsal 100 23 Humeral 100 23 Alar 100 23 Femoral 100 23 Crural 5 95 22 Caudal 4 96 23 Ventral 100 23 Morphometric Data Measurements Mean ± SD Min Max n Weight 14.85 ± 1.437 10.4 16.5 23 Tarsus 19.77 ± 0.888 18.0 21.5 23 Wing Chord 32.93 ± 1.779 28.5 36.4 23 Culmen 5.16 ± 0.455 4.2 6.0 23 Outer Primary 19.35 ± 2.731 14.0 22.2 15 Outer Rectrix 3.85 ± 0.918 2.0 6.0 21 Longest Broken Primary 5.27 ± 1.280 3.0 8.0 15 Length 71.53 ± 5.805 60.0 83.0 15 Gape 12.75 ± 0.507 12.0 13.5 15 General Description All tracts have pins that are clearly unsheathed. Upper wing covert pins clearly unsheathed. Unsheathed feathers of ventral tract cinnamon colored and form two broad strips. Unsheathed feathers of dorsal tract form rust colored strip on back. Very alert; flaps and kicks quickly, and nestling usually will not remain still. Turns neck and head to look around. May give fledgling “chip” locator call. Young are prone to “jump” after this day. Use caution. Carolina Wren (Thryothorus ludovicianus ludovicianus) continued Results 21 Species Accounts Wrentit Chamea fasciata rufula Data collection: Point Reyes National Seashore, Marin Co., California. Nests: n = 2 (2003), n = 2 (2004), n = 7 (2005) Nest Period Data: Average (range), n = number of nests Building: 6-7 (3 - 14) days (Geupel and Ballard, 2002) Clutch size: 3.6 (1 - 5) eggs, n = 733 Incubation: 14.9 (11 - 18) days, n = 192 Nestling: 14.6 (11 - 19) days, n = 242 Indicator Table: Wrentit visual characteristics typical at a given age. Alar pins centered on dorsal wing surface 1 Alar pins stretched towards posterior edge of wing 2 Crural tract just becoming visible 3 Alar pins have extended to the wing edge 3 Primary and secondary pins appear ready to emerge 4 Capital, dorsal, and humeral tracts just emerged 6 Eyes begin to open 6-7 Alar pin tips are pale, ready to unsheathe 8 Alar pins begin to unsheathe 9 Young appear soft due to extent of unsheathing 10 Indicator characteristics Age Indicator characteristics Age General Feather Development: Wrentit feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N V N V V N V N N V N 2 N V V V V V N N V N V 3 V V V V V N V V V 4 V V V V P V V V V 5 V V P V P V P V V V V P 6 V P V P U V P U P V P U V V P V P U 7 P P U P U P U V P U V P U V P U P U 8 U U U P U U V P U P U P U 9 U U U U U P U U U 10 U U U U U U U U 11 U U U U U U U U 22 A Guide to Nestling Development and Aging in Altricial Passerines Day 1 Key Visual Indicators: - Skin appears uniformly fleshy pink except around eyes - Capital tract pins are not visible - Alar pins are centered along dorsal wing surface Feather Tract Development Tract N V P U F n Capital 100 6 Dorsal 100 6 Humeral 50 50 6 Alar 100 6 Femoral 83 17 6 Crural 100 6 Caudal 50 50 6 Ventral 100 6 Morphometric Data Measurements Mean ± SD Min Max n Weight 1.78 ± 0.248 1.6 2.1 6 Tarsus 6.27 ± 1.310 4.58 7.2 6 Wing Chord 4.31 ± 0.696 3.5 5.17 6 Culmen 1.93 ± 0.305 1.6 2.27 4 Outer Primary 0 0 0 6 Outer Rectrix 0 0 0 6 Longest Broken Primary 0 0 0 5 Length 32.5 ± 1.291 31.0 34.0 4 Gape 7.32 ± 0.282 7.08 7.7 4 General Description Eyes and ears closed. Ears visible as indentations. Bill is ocher with orange yellow, with an ashy olive tip, and a sulfur yellow gape. The nares are just barely visible. A very small white egg tooth is visible. Skin color is uniformly fleshy pink throughout head and body except for around the eyes, which are blackish gray. Head and body are completely naked. Capital, dorsal, humeral, and caudal tracts are visible as very light gray areas formed by faintly pigmented pins. Femoral and ventral tracts not visible. Flight feather pins on the wings are distinguishable as individual pins and are centered on the wing as a gray band. Limbs are moved around slowly. Young are struggling to lift head up. Wrentit (Chamea fasciata rufula) continued Day 2 Key Visual Indicators: - Back of head beginning to darken as capital tract pins begin to darken - Dorsal tract area beginning to darken forming a light gray stripe - Alar pins stretched towards posterior edge of wing Feather Tract Development Tract N V P U F n Capital 27 73 11 Dorsal 100 11 Humeral 100 11 Alar 100 11 Femoral 100 11 Crural 100 11 Caudal 18 82 11 Ventral 55 45 11 Morphometric Data Measurements Mean ± SD Min Max n Weight 2.43 ± 0.548 1.7 3.4 9 Tarsus 7.69 ± 1.024 6.02 9.13 11 Wing Chord 5.0 ± 0.597 4.0 6.03 11 Culmen 2.22 ± 0.277 1.93 2.67 9 Outer Primary 0 0 0 11 Outer Rectrix 0 0 0 11 Longest Broken Primary 0 0 0 11 Length 33.8 ± 2.348 29.0 36.0 10 Gape 8.02 ± 0.605 6.87 8.94 10 General Description Eyes and ears closed. Nares visible as a short notch. Egg tooth may still be present, though not as prominent as day 1. Skin is fleshy pink except for the area around eyes, top of head, and dorsal tract areas, which are blackish gray and wrinkled. Capital tract pins visible as light spots. Femoral tract is just visible as spotting. Dorsal tract is visible as a blackish gray stripe (1-2 mm wide). Ventral tract visible as gray spotting down the throat and sides of chest, becoming flesh colored along belly. Alar pins are individually distinguishable and are stretched towards the posterior edge of the wing. Humeral tract is visible as spotting forming a light gray band. Crural tract is not visible. Caudal tract is just visible. Young are able to move limbs quickly; are uncoordinated. Results 23 Day 3 Key Visual Indicators: - Alar pins have grown to the posterior edge of wing and press up on dorsal wing surface - Crural tract just becoming visible as gray flecks Feather Tract Development Tract N V P U F n Capital 100 13 Dorsal 100 13 Humeral 100 13 Alar 100 13 Femoral 100 13 Crural 38 62 13 Caudal 100 13 Ventral 100 13 Morphometric Data Measurements Mean ± SD Min Max n Weight 3.51 ± 0.668 2.4 4.5 13 Tarsus 9.17 ± 0.937 7.64 10.73 13 Wing Chord 5.54 ± 0.520 5.0 6.51 13 Culmen 2.52 ± 0.229 2.16 2.88 12 Outer Primary 0 0 0 13 Outer Rectrix 0 0 0 13 Longest Broken Primary 0 0 0 12 Length 38.08 ± 2.275 34.0 42.0 12 Gape 9.16 ± 0.688 8.25 9.94 12 General Description Eyes closed. Ears closed. Remnant of egg tooth still may be visible. Skin a darker more purple fleshy pink. Skin around head is dark gray with much wrinkling. Capital tract is visible as gray flecks. Humeral tract is visible as a dark stripe about 5 mm in length. Dorsal tract is visible as a dark gray stripe with a separate darkened area near base of tail bud. Alar pins have extended to the edge of the wing and are pressing up on the dorsal surface of the wing. Femoral tract is visible as dark gray flecks in 2-3 short rows. Crural tract is just visible as a few gray flecks. Ventral tract is visible as gray flecks down the throat and sides of chest. Wrentit (Chamea fasciata rufula) continued Day 4 Key Visual Indicators: - Primary and secondary pins appear ready to emerge Feather Tract Development Tract N V P U F n Capital 100 12 Dorsal 100 12 Humeral 100 12 Alar 92 8 12 Femoral 100 12 Crural 100 12 Caudal 100 12 Ventral 100 12 Morphometric Data Measurements Mean ± SD Min Max n Weight 4.42 ± 0.804 3.4 6.2 12 Tarsus 10.60 ± 1.406 8.01 13.02 12 Wing Chord 6.96 ± 1.573 5.5 10.0 12 Culmen 2.55 ± 0.230 2.05 2.8 12 Outer Primary 0.08 ± 0.289 0 1.0 12 Outer Rectrix 0 0 0 12 Longest Broken Primary 0 0 0 12 Length 42.0 ± 2.697 39.0 47.0 12 Gape 9.80 ± 0.824 8.61 11.1 12 General Description Eyes and ears closed. Nestlings are mostly naked. Capital tract is visible as flecks covering the head. Humeral and femoral tracts are visible as short dark gray stripes. Primary and secondary pins appear ready to emerge. Some body pins are pressing out against skin. Dorsal tract appears as a solid dark gray wrinkled stripe. Crural tract is visible as gray flecks. Individual caudal pins are distinguishable. Small hair-like projections appear where the rectrices will protrude. Ventral tract appears as a darker, more pronounced stripe composed of gray pins anteriorly and flesh colored pins posteriorly. Young sporadically lift body and head by kicking with their legs and flapping wings. 24 A Guide to Nestling Development and Aging in Altricial Passerines Day 5 Key Visual Indicators: - Capital, dorsal, humeral, and femoral tracts pushing up on skin surface, appear ready to emerge - Alar pins typically just emerged Feather Tract Development Tract N V P U F n Capital 100 10 Dorsal 90 10 10 Humeral 80 20 10 Alar 40 60 10 Femoral 100 10 Crural 100 10 Caudal 100 10 Ventral 90 10 10 Morphometric Data Measurements Mean ± SD Min Max n Weight 5.61 ± 0.522 5.1 6.9 10 Tarsus 12.41 ± 1.664 9.56 15.15 10 Wing Chord 9.7 ± 2.275 6.0 13.0 10 Culmen 3.06 ± 0.162 2.84 3.3 8 Outer Primary 0.35 ± 0.242 0 0.5 10 Outer Rectrix 0 0 0 9 Longest Broken Primary 0 0 0 8 Length 43.75 ± 2.550 40.0 46.0 8 Gape 10.60 ± 0.362 10.17 11.03 8 General Description Eyes closed. Ear canals may begin to open. Nestlings are mostly naked with most feather tract pins now pushing up on the skin surface. Dark bill tip color now extends to all other parts of the bill except for the rictus and nares. The rictus is turning a deeper yellow and the area around the nares is an olive buff yellow. Capital tract pins have begun to push up on the skin. Anterior humeral pins and some ventral pins may have just emerged. Some or all primaries and secondaries typically emerging. Wrentit (Chamea fasciata rufula) continued Day 6 Key Visual Indicators: - Capital, dorsal, and humeral tracts just emerged - Eyes typically begin to open - Outer primary measures 1-2mm Feather Tract Development Tract N V P U F n Capital 43 57 14 Dorsal 14 64 22 14 Humeral 14 72 14 14 Alar 100 14 Femoral 50 36 14 14 Crural 100 14 Caudal 71 29 14 Ventral 29 57 14 14 Morphometric Data Measurements Mean ± SD Min Max n Weight 6.96 ± 0.592 5.7 8.0 14 Tarsus 14.44 ± 1.715 11.66 17.79 14 Wing Chord 12.61 ± 3.420 6.0 19.5 14 Culmen 3.13 ± 0.268 2.53 3.53 12 Outer Primary 1.35 ± 0.798 0 30.0 13 Outer Rectrix 0 0 0 13 Longest Broken Primary 0 0 0 12 Length 47.27 ± 2.149 45.0 51.0 11 Gape 10.98 ± 0.484 10.24 11.99 12 General Description Eyes may begin to partially open. Ear canals appear open. Nestlings appear “spiky”, with many pins now just out above the skin surface. The area around the nares is turning ash olive in color. Most primary and secondary pins have emerged. 9th primary measures 1-2 mm. Some wing covert pins may have emerged. Ventral pins may be just out with the exception of those anterior to the furculum. Crural tract pins have not emerged. Caudal tract typically not emerged. Results 25 Day 7 Key Visual Indicators: - Dorsal, humeral, femoral, and ventral tracts begin to unsheathe - Caudal pins have emerged - Eyes typically partially open Feather Tract Development Tract N V P U F n Capital 85 15 13 Dorsal 69 31 13 Humeral 38 62 13 Alar 85 15 13 Femoral 8 38 54 13 Crural 70 15 15 13 Caudal 15 77 8 13 Ventral 38 62 13 Morphometric Data Measurements Mean ± SD Min Max n Weight 7.74 ± 0.900 6.8 10.0 14 Tarsus 16.16 ± 1.430 14.15 18.7 14 Wing Chord 14.76 ± 2.793 9.0 20.0 14 Culmen 3.44 ± 0.195 3.17 3.79 12 Outer Primary 2.75 ± 1.141 1.0 5.0 14 Outer Rectrix 0.32 ± 0.249 0 0.5 14 Longest Broken Primary 0.04 ± 0.144 0 0.5 12 Length 48.42 ± 2.999 44.0 54.0 12 Gape 11.15 ± 0.513 10.23 12.23 12 General Description Eyes are partially open. Bill continues to darken. Dorsal, humeral, femoral, and ventral tracts begin to unsheathe. Most pins of the remiges have clearly emerged. P9 measures about 5 mm. Wrentit (Chamea fasciata rufula) continued Day 8 Key Visual Indicators: - Most feather tracts typically just unsheathing except for crural and caudal tract Feather Tract Development Tract N V P U F n Capital 37.5 62.5 8 Dorsal 100 8 Humeral 100 8 Alar 12.5 87.5 8 Femoral 100 8 Crural 75 25 8 Caudal 62.5 37.5 8 Ventral 12.5 87.5 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 8.75 ± 0.327 8.4 9.2 6 Tarsus 17.25 ± 1.032 15.31 18.38 8 Wing Chord 18.2 ± 1.010 17.0 20.0 8 Culmen 3.68 ± 0.200 3.38 3.97 6 Outer Primary 4.29 ± 0.907 3.0 5.18 8 Outer Rectrix 0.63 ± 0.231 0.5 1.0 8 Longest Broken Primary 0 0 0 6 Length 50.67 ± 1.033 49.0 52.0 6 Gape 11.2 ± 0.451 10.61 11.81 6 General Description Eyes are partially open. Bill continues to darken. All tracts except crural and caudal are now typically beginning to unsheathe. Remiges have lengthened, and their tips may appear white and ready to unsheathe. P9 measures about 7 mm. Some wing coverts and secondaries may be unsheathing. Movement is constant but uncoordinated. 26 A Guide to Nestling Development and Aging in Altricial Passerines Day 9 Key Visual Indicators: - Primary tips appear pale and ready to unsheathe or begin to unsheathe - All feather tracts are unsheathing - Secondary pins begin to unsheathe Feather Tract Development Tract N V P U F n Capital 100 10 Dorsal 100 10 Humeral 100 10 Alar 100 10 Femoral 100 10 Crural 20 80 10 Caudal 100 10 Ventral 100 10 Morphometric Data Measurements Mean ± SD Min Max n Weight 9.85 ± 0.463 9.1 10.5 11 Tarsus 19.37 ± 1.696 16.97 22.73 12 Wing Chord 22.08 ± 2.712 19.0 28.0 12 Culmen 3.87 ± 0.428 3.29 4.55 10 Outer Primary 7.74 ± 1.402 6.0 10.0 12 Outer Rectrix 1.81 ± 1.269 0.5 5.0 12 Longest Broken Primary 1.5 ± 0.972 0 3.0 10 Length 52.6 ± 2.633 49.0 57.0 10 Gape 11.25 ± 0.485 10.49 11.79 10 General Description Eyes are open most of the time. Nestlings beginning to appear soft due to the extent of the unsheathed pin feathers. Bill darkening may begin to extend into the gape. All body pins continue to unsheathe. Primaries and secondaries may begin to unsheathe. P9 measures about 10 mm. Wrentit (Chamea fasciata rufula) continued Day 10 Key Visual Indicators: - Capital, dorsal, and ventral tracts appear feathered due to the extent of exposed feathers - Young appear alert, though movement is not well coordinated - Primary pins unsheathing Feather Tract Development Tract N V P U F n Capital 100 6 Dorsal 100 6 Humeral 100 6 Alar 100 6 Femoral 100 6 Crural 100 6 Caudal 100 6 Ventral 100 6 Morphometric Data Measurements Mean ± SD Min Max n Weight 10.7 ± 0.544 10.0 11.4 6 Tarsus 20.50 ± 1.325 19.11 21.98 6 Wing Chord 24.67 ± 1.633 23.0 27.0 6 Culmen 3.93 ± 0.214 3.72 4.15 4 Outer Primary 8.44 ± 1.512 6.0 10.52 6 Outer Rectrix 2.85 ± 0.943 2.0 4.0 6 Longest Broken Primary 2.75 ± 0.957 2.0 4.0 4 Length 54.0 ± 1.826 52.0 56.0 4 Gape 10.96 ± 0.386 10.4 11.29 4 General Description Eyes are open most of the time. Nestlings appear feathered with apteria mostly covered along back and flanks. Most alar pins are unsheathing. Body pins continue to unsheathe. P9 measures about 12 mm. Unsheathed portion of rectrices about 2 mm. Young are typically ready for banding. Results 27 Species Accounts Sprague’s Pipit Anthus spragueii Data collection: Bowdoin National Wildlife Refuge, Phillips County, Montana. Nests: n = 1 (2004). Nest Period Data: Average (range). n = number of nests Building: No data Clutch size: 4.6 (1 - 6) eggs, n = 123 Incubation: 12.2 (7 - 15) days, n = 85 Nestling: 13.1 (9 - 17) days, n = 17 Indicator Table: Sprague’s Pipit visual characteristics typical at a given age. No feather tracts visible below skin 1 Feather tracts may be just visible as stippling on skin or small dark spots 2 No data 3 Eyes partially open. Alar tracts beginning to emerge 4 Eyes appear fully open. Pin feathers are out on some tracts 5 Pin feathers emerged on all tracts 6 Some tracts begin to unsheathe 7 All tracts begin to unsheathe. Primaries begin to unsheathe 8 No data 9 Primaries are unsheathed about 1 mm 10 Sheathes on most feather tracts no longer visible or obscured by feathers 11 Indicator characteristics Age Indicator characteristics Age General Feather Development: Sprague’s Pipit feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N N N N N N N N 2 V V V V N N V 3 4 V V V P V V V V 5 V P P P P V V P 6 P P P P P P P P 7 P U U P U P P U 8 U U U U U U U U 9 10 U U U U U U U U 11 U U U U U U U U 12 U U U U U U U U 28 A Guide to Nestling Development and Aging in Altricial Passerines Sprague’s Pipit (Anthus spragueii) continued Day 1 Key Visual Indicators: - No feather tracts visible beneath skin - Eyes closed - Nestling may be curled into a ball Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 2.5 2.2 2.8 2 Tarsus 6.59 6.00 7.19 2 Wing Chord 6.0 6.0 6.0 2 Culmen 2.17 2.08 2.27 2 Outer Primary 0 0 0 2 Outer Rectrix 0 0 0 2 Longest Broken Primary 0 0 0 2 Length 37.5 37.0 38.0 2 Gape 7.86 7.78 7.95 2 General Description Skin and legs salmon colored. Long, light grey (almost white) down on most feather tracts but no tracts are visible beneath skin. Rictus yellow. Eyes closed. May display weak or shaky gaping. Can’t hold head up. Lays flat on belly or may curl into ball shape. Quiet. Day 2 Key Visual Indicators: - Eyes closed - Most feather tracts (except caudal and crural) becoming visible as stippling on skin or very small dark spots Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 3.3 3.3 3.4 2 Tarsus 7.81 7.76 7.86 2 Wing Chord 7.0 7.0 7.0 2 Culmen 2.39 2.32 2.46 2 Outer Primary 0 0 0 2 Outer Rectrix 0 0 0 2 Longest Broken Primary 0 0 0 2 Length 40.5 40.0 41.0 2 Gape 9.08 8.88 9.29 2 General Description Appearance very much the same as Day 1. Most feather tracts (except caudal and crural) becoming visible as small dark spots under skin or stippling on skin surface. Eyes closed. More movement than Day 1 but still weak and shaky. Quiet. Results 29 Day 3 No data Sprague’s Pipit (Anthus spragueii) continued Day 4 Key Visual Indicators: - Eyes partially open - All feather tracts visible with alar just beginning to emerge Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 6.7 6.6 6.8 2 Tarsus 11.38 10.97 11.80 2 Wing Chord 11.0 10.0 12.0 2 Culmen 3.27 3.16 3.38 2 Outer Primary 0 0 0 2 Outer Rectrix 0 0 0 2 Longest Broken Primary 0 0 0 2 Length 48.5 48.0 49.0 2 Gape 11.38 10.94 11.82 2 General Description Skin, legs and bill pink. Rictus yellow. Still downy. All tracts visible under skin. Alar tract just beginning to emerge. Eyes may be partially open. Movement is stronger but not held for long. One nestling made soft clicking noises. 30 A Guide to Nestling Development and Aging in Altricial Passerines Day 5 Key Visual Indicators: - Eyes fully open - Pin feathers on wings and most body tracts Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 50 50 2 Crural 100 2 Caudal 100 2 Ventral 50 50 2 Morphometric Data Measurements Mean Min Max n Weight 8.0 7.8 8.3 2 Tarsus 13.47 13.18 13.76 2 Wing Chord 12.0 11.0 13.0 2 Culmen 3.50 3.49 3.52 2 Outer Primary 1.0 1.0 1.0 2 Outer Rectrix 0 0 0 2 Longest Broken Primary 0 0 0 2 Length 50.5 50.0 51.0 2 Gape 12.23 12.11 12.35 2 General Description Eyes fully open. Pins emerging on dorsal, alar and humeral tracts and may be emerging on ventral and femoral. Not much movement, some gaping. Quiet. Sprague’s Pipit (Anthus spragueii) continued Day 6 Key Visual Indicators: - Pin feathers have emerged on all tracts Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 11.7 11.2 12.2 2 Tarsus 15.75 15.33 16.17 2 Wing Chord 17.0 16.0 18.0 2 Culmen 3.92 3.88 3.97 2 Outer Primary 3.5 3.0 4.0 2 Outer Rectrix 0.5 0 1.0 2 Longest Broken Primary 0 0 0 2 Length 53.0 51.0 55.0 2 Gape 12.79 12.77 12.81 2 General Description Down on dorsal, capital and alar tracts. Down is approx. 10 mm long but getting more sparse. Pin feathers have emerged on all tracts, however caudal may be barely emerging. May balance on rump and tarsus. Soft clicking noises. Results 31 Day 7 Key Visual Indicators: - Some feathers beginning to unsheathe Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 50 50 2 Alar 100 2 Femoral 50 50 2 Crural 100 2 Caudal 100 2 Ventral 50 50 2 Morphometric Data Measurements Mean Min Max n Weight 13.4 12.9 14.0 2 Tarsus 18.13 17.90 18.36 2 Wing Chord 21.0 20.0 22.0 2 Culmen 4.35 4.14 4.57 2 Outer Primary 6.5 6.0 7.0 2 Outer Rectrix 1.5 1.0 2.0 2 Longest Broken Primary 0 0 0 2 Length 58.0 56.0 60.0 2 Gape 13.44 13.24 13.64 2 General Description Sparse down on dorsal, capital and alar tracts. Dorsal pins unsheathing and possibly ventral, femoral and humeral. More alert. Makes soft clicking noises and occasionally a soft chirp. Sprague’s Pipit (Anthus spragueii) continued Day 8 Key Visual Indicators: - All tracts unsheathing - Primaries beginning to unsheathe Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 15.0 13.9 16.1 2 Tarsus 19.79 19.71 19.88 2 Wing Chord 27.0 26.0 28.0 2 Culmen 4.54 4.47 4.62 2 Outer Primary 10.0 9.0 11.0 2 Outer Rectrix 3.5 3.0 4.0 2 Longest Broken Primary 0 0 0 2 Length 62.5 62.0 63.0 2 Gape 13.71 13.69 13.73 2 General Description Down same as Day 7. All feather tracts unsheathing. Primaries just beginning to unsheathe. May make soft clicking noises. 32 A Guide to Nestling Development and Aging in Altricial Passerines Day 9 No data Sprague’s Pipit (Anthus spragueii) continued Day 10 Key Visual Indicators: - Primary pins unsheathing about 1 mm Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 19.3 18.4 20.3 2 Tarsus 21.98 21.72 22.24 2 Wing Chord 36.5 34.0 39.0 2 Culmen 5.09 4.93 5.26 2 Outer Primary 17.0 15.0 19.0 2 Outer Rectrix 7.5 7.0 8.0 2 Longest Broken Primary 3.5 1.0 6.0 2 Length 76.0 75.0 77.0 2 Gape 13.86 13.76 13.96 2 General Description Down still apparent on head and back and a little on the wings. Most feathers well out of sheaths except around the face. Primaries have emerged. Feathers on head and back dark, chest is brown and belly is tan/white. Much more active with some soft clicking and chirping. Results 33 Sprague’s Pipit (Anthus spragueii) continued Day 12 Key Visual Indicators: - Appearance similar to Day 11 - Base of remiges in sheath, but obscured by exposed feathers Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 19.0 18.1 20.0 2 Tarsus 22.82 22.57 23.08 2 Wing Chord 45.5 43.0 48.0 2 Culmen 5.61 5.33 5.89 2 Outer Primary 24.0 22.0 26.0 2 Outer Rectrix 10.5 10.0 11.0 2 Longest Broken Primary 13.0 12.0 14.0 2 Length Gape 13.24 13.12 13.36 2 General Description Down very sparse on back and head, almost gone from the wings. Base of remiges still in sheath, but obscured by exposed feathers. Very active, standing and jumping. Some chirping/squawking noises mostly while trying to escape. Day 11 Key Visual Indicators: - Sheaths on most feather tracts are no longer visible except on wings Feather Tract Development Tract N V P U F n Capital 100 2 Dorsal 100 2 Humeral 100 2 Alar 100 2 Femoral 100 2 Crural 100 2 Caudal 100 2 Ventral 100 2 Morphometric Data Measurements Mean Min Max n Weight 18.8 18.3 19.4 2 Tarsus 22.4 22.3 22.5 2 Wing Chord 41.0 38.0 44.0 2 Culmen 5.22 5.18 5.27 2 Outer Primary 22.0 20.0 24.0 2 Outer Rectrix 9.5 9.0 10.0 2 Longest Broken Primary 6.0 3.0 9.0 2 Length 78.0 77.0 79.0 2 Gape 13.42 13.29 13.55 2 General Description Still some sparse down. Sheaths at bottom of all feathers but only visible on wings. Very active but quiet. 34 A Guide to Nestling Development and Aging in Altricial Passerines Species Accounts Song Sparrow Melospiza melodia gouldii Data collection: Point Reyes National Seashore, Marin County, California. Nests: n = 11 (2004), n = 9 (2005). Nest Period Data: Average (range), n = number of nests Building: No data Clutch size: 3 (2 - 5) eggs, n =198 Incubation period: 13 (12 - 16) days, n = 40 Nestling period: 9 (8 - 12) days, n = 55 Indicator Table: Song Sparrow visual characteristics typical at a given age. Alar pins in a band centered across wing 1 Alar pins have grown towards posterior edge of wing 2 Ventral tract appears as spots from furculum to mid chest 2 Some primary pins are just out 3 All primary and secondary pins are out 3-4 Outer primaries about 2mm long 4 Eyes just beginning to open 5 Some contour pins begin to unsheathe 5 Eyes appear fully open 5-6 Primary pins beginning to unsheathe 7 All feather tracts are unsheathing 7-8 Indicator characteristics Age Indicator characteristics Age General Feather Development: Song Sparrow feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N V N V N V V N V N V N N V 2 N V V N V V P N V N V N V N V 3 V V P V P V P V P N V N V V P 4 V P V P V P P V P V P V P V P 5 V P P U P P V P V P V P V P U 6 V P P U P U P U V P U V P U V P P U 7 P U P U P U P U P U P U V P U P U 8 U U U U U U P U U Results 35 Day 1 Key Visual Indicators: - Alar pins centered across wing and not individually distinguishable - Young are small (egg size) - Down may appear moist - Egg tooth is prominent/visible Feather Tract Development Tract N V P U F n Capital 60 40 20 Dorsal 5 95 20 Humeral 15 85 20 Alar 100 20 Femoral 80 20 20 Crural 95 5 20 Caudal 100 20 Ventral 70 30 20 Morphometric Data Measurements Mean ± SD Min Max n Weight 2.28 ± 0.549 1.5 3.8 20 Tarsus 7.02 ± 0.944 5.64 9.04 20 Wing Chord 4.65 ± 0.671 4.0 6.5 20 Culmen 2.14 ± 0.228 1.84 2.9 20 Outer Primary 0 0 0 12 Outer Rectrix 0 0 0 12 Longest Broken Primary 0 0 0 20 Length 36.53 ± 4.128 28.0 46.0 19 Gape 7.46 ± 0.481 6.87 8.88 20 General Description Eyes closed. Ears are closed, though a small indentation is visible. Bill is orange/grey with, some brown at the tip and a yellowish/white rictus. The egg tooth is visible near the tip of the upper mandible. Skin is a light orange with some pink areas. Light gray down is present on capital, dorsal, alar, humeral, and femoral tracts. Eyelids appear large and dark gray. Ventral tract is visible as indentations on skin. Dorsal pins are visible as a very light gray stripe. Capital tract pins very light in color, small, and just visible. Femoral tract is typically not visible. Humeral tract is visible as a very light gray single line. Caudal and crural tracts are not visible. Young able to move all limbs very slowly and lift head briefly. Song Sparrow (Melospiza melodia gouldii) continued Day 2 Key Visual Indicators: - Alar pins individually distinguishable - Alar pins stretched towards posterior edge of wing Feather Tract Development Tract N V P U F n Capital 3 97 32 Dorsal 100 32 Humeral 3 97 32 Alar 97 3 32 Femoral 31 69 32 Crural 55 45 31 Caudal 68 32 31 Ventral 6 94 32 Morphometric Data Measurements Mean ± SD Min Max n Weight 3.434 ± 0.695 2.5 5.9 32 Tarsus 8.54 ± 1.018 6.06 10.46 32 Wing Chord 5.45 ± 0.766 4.0 8.0 32 Culmen 2.41 ± 0.303 1.42 2.83 32 Outer Primary 0.03 ± 0 0 0.5 16 Outer Rectrix 0 0 0 16 Longest Broken Primary 0 0 0 32 Length 38.91 ± 2.97 35.0 48.0 32 Gape 8.68 ± 0.746 7.23 10.02 32 General Description Eyes closed. Ears closed. Capital tract visible as gray flecks. Dorsal pins visible as gray flecks forming a stripe. Capital tract visible as gray flecks. Alar pins distinguishable as individual pins. Femoral tract is visible as a few gray flecks. Humeral tract is visible as a gray band. Caudal tract is visible as a single gray line. Crural tract is visible as a few gray flecks. Ventral tract is visible as gray spotting from furculum to about mid-chest; visible as skin markings posteriorly. May have small hair-like protrusions on wing where flight feathers will protrude. Young are able to quietly chirp and move all limbs. 36 A Guide to Nestling Development and Aging in Altricial Passerines Day 3 Key Visual Indicators: - Some to all remiges emerging - P9 measures about 1mm Feather Tract Development Tract N V P U F n Capital 100 30 Dorsal 97 3 30 Humeral 93 7 30 Alar 17 83 30 Femoral 93 7 30 Crural 7 93 30 Caudal 10 90 30 Ventral 97 3 30 Morphometric Data Measurements Mean ± SD Min Max n Weight 5.45 ± 1.157 3.1 9.0 30 Tarsus 10.85 ± 1.417 8.63 14.37 30 Wing Chord 8.15 ± 1.885 5.0 12.0 30 Culmen 2.84 ± 0.273 2.3 3.57 30 Outer Primary 0.75 ± 0.429 0.5 2.0 18 Outer Rectrix 0 0 0 18 Longest Broken Primary 0 0 0 30 Length 42.5 ± 2.968 37.0 49.0 30 Gape 10.24 ± 0.820 7.98 11.77 30 General Description Eyes closed. Ears closed. Capital tract visible as gray flecks in a band with smaller flecks around the ear. Dorsal pins are visible as a gray stripe. Some or all remiges are emerging. P9 is less than 1mm. Humeral and femoral tracts darker, still not out. Caudal tract line a bit thicker. Crural tract pins visible as flecks, still not out. Ventral tract is visible as gray flecks from furculum to mid-chest. Some spotting on chin is visible. Pins along belly are light in color and still not out. Young lifting whole body and head up with forelimbs and legs. Song Sparrow (Melospiza melodia gouldii) continued Day 4 Key Visual Indicators: - All remiges have emerged - P9 measures about 2 mm - Most body pins appear to be just out or pushing up on skin surface - Eyes may be partially open Feather Tract Development Tract N V P U F n Capital 85 15 26 Dorsal 58 42 26 Humeral 46 54 26 Alar 100 26 Femoral 80 19 26 Crural 96 4 26 Caudal 96 4 26 Ventral 58 42 26 Morphometric Data Measurements Mean ± SD Min Max n Weight 7.64 ± 1.495 3.6 10.3 25 Tarsus 13.44 ± 1.548 10.24 16.65 26 Wing Chord 11.94 ± 1.899 8.0 17.0 26 Culmen 3.27 ± 0.285 2.68 3.96 26 Outer Primary 2.25 ± 0.913 1.0 4.5 16 Outer Rectrix 0 0 0 16 Longest Broken Primary 0 0 0 26 Length 48.0 ± 3.544 40.0 55.0 26 Gape 11.25 ± 0.626 9.53 12.02 26 General Description Eyes may partially open. Ears open. Most body pins appear to be out or pushing up against the skin surface. A few femoral pins may be out or pushing on skin. Humeral pins are out. All other pins are pushing up on the skin except for the crural tract. All remiges have emerged. P9 measures about 2mm. Ventral pins may be just out or pushing on skin and much more pronounced. Skin color becoming darker pink. Down is still present. Young are able to turn over on to back. Results 37 Day 5 Key Visual Indicators: - P9 measures about 4mm - Most pin feathers are out - Some body pins may begin unsheathing Feather Tract Development Tract N V P U F n Capital 50 50 26 Dorsal 96 4 26 Humeral 100 26 Alar 100 26 Femoral 4 96 26 Crural 58 42 26 Caudal 85 15 26 Ventral 4 92 4 26 Morphometric Data Measurements Mean ± SD Min Max n Weight 9.86 ± 1.757 6.0 13.2 21 Tarsus 15.17 ± 1.549 11.44 18.04 26 Wing Chord 15.48 ± 2.012 11.0 22.0 26 Culmen 3.58 ± 0.306 3.02 4.18 26 Outer Primary 4.0 ± 1.676 2.0 8.0 14 Outer Rectrix 0.071 ± 0.182 0 0.5 14 Longest Broken Primary 0 0 0 26 Length 50.75 ± 2.625 46.0 56.0 24 Gape 11.95 ± 0.597 10.7 13.08 26 General Description Eyes may be opened partially. Capital tract pins are just out. Dorsal pins are out from nape to about mid-back. Some crural tract pins are out. Humeral and femoral pins are out 1 - 2 mm. Caudal tract shows hair-like projections where the rectrices will emerge. Ventral pins are out about 1 mm. P9 measures about 4 mm. Small subcutaneous pins are visible around ear and cloaca. Song Sparrow (Melospiza melodia gouldii) continued Day 6 Key Visual Indicators: - P9 measures about 6mm - All dorsal pins are out Feather Tract Development Tract N V P U F n Capital 4 96 26 Dorsal 62 38 26 Humeral 54 46 26 Alar 92 8 26 Femoral 4 42 54 26 Crural 4 73 23 26 Caudal 23 77 26 Ventral 35 65 26 Morphometric Data Measurements Mean ± SD Min Max n Weight 11.73 ± 2.396 3.3 14.7 26 Tarsus 17.62 ± 2.032 12.05 20.74 26 Wing Chord 19.92 ± 3.215 11.0 24.0 26 Culmen 3.92 ± 0.404 2.91 4.62 26 Outer Primary 7.43 ± 2.065 3.5 10.0 14 Outer Rectrix 1.07 ± 0.829 0 2.0 14 Longest Broken Primary 0.038 ± 0.196 0 1.0 26 Length 54.46 ± 4.101 42.0 65.0 26 Gape 12.30 ± 0.744 9.97 13.31 26 General Description Eyes open. Capital tract pins are out about 1mm. Dorsal pins are out from nape to tail bud. Most crural tract pins are out. Humeral and femoral pins are out about 2 mm. Pins around ear are just emerging. Rectrices may be just emerging. Ventral pins are out about 2 mm. P9 measures about 6 mm. Tips of primaries may appear whitish and ready to break 38 A Guide to Nestling Development and Aging in Altricial Passerines Day 7 Key Visual Indicators: - Flight feathers have begun to unsheathe - All feather tracts are unsheathing - Eyes may appear fully open Feather Tract Development Tract N V P U F n Capital 56 44 25 Dorsal 8 92 25 Humeral 4 96 25 Alar 24 76 25 Femoral 4 96 25 Crural 28 72 25 Caudal 8 56 36 25 Ventral 4 96 25 Morphometric Data Measurements Mean ± SD Min Max n Weight 13.80 ± 1.641 9.2 15.7 26 Tarsus 19.66 ± 1.778 14.85 22.13 27 Wing Chord 24.35 ± 3.059 17.0 30.0 26 Culmen 4.38 ± 0.333 3.7 5.05 27 Outer Primary 10.69 ± 2.462 5.0 15.0 16 Outer Rectrix 2.91 ± 1.725 0 6.0 16 Longest Broken Primary 0.796 ± 1.031 0 4.0 27 Length 58.13 ± 4.174 54.0 70.0 24 Gape 12.34 ± 0.535 11.13 13.36 27 General Description Dorsal pins are about 30% unsheathing. Capital tract pins are about 2 mm. Some crural pins are unsheathing. Some femoral pins are unsheathing. Most humeral pins are unsheathing. Flight feathers have begun to unsheathe. Ventral pins are mostly unsheathed with the exception of the throat area. Young are typically ready for banding. Young are prone to “jump” after this day. Song Sparrow (Melospiza melodia gouldii) continued Results 39 Species Accounts Chestnut-collared Longspur Calcarius ornatus Data collection: Bowdoin National Wildlife Refuge, Phillips County, Montana. Nests: n = 1 (2004), n = 1 (2005), n = 5 (2006) Nest Period Data: Average (range), n = number of nests Building: no data Clutch size: 4.1 (1 - 7) eggs, n = 764 Incubation: 11.0 (7 - 15) days, n = 553 Nestling: 11.3 (7 - 15) days, n = 166 Indicator Table: Chestnut-collared Longspur visual characteristics typical at a given age. No feather tracts are visible 1 Alar, dorsal, and ventral tracts becoming visible 2 Alar pins have grown towards posterior edge of wing and pressing on skin surface 3 Eyes begin to open. Alar pins typically emerged 4 Pin feathers have emerged on all tracts 5 Pins begin to unsheathe. Primary tips pale and ready to unsheathe 6 Primary pins begin to unsheathe 7 All feather tracts are unsheathing 8 Indicator characteristics Age Indicator characteristics Age General Feather Development: Chestnut-collared Longspur feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N N N N N N N N V 2 N N V N N V N N N N V 3 N V N V N V N V P N V N V N V V P 4 N V N V P N V P N V P V P N V P N V P V P 5 N V P V P V P V P V P N V P N V P V P 6 V P U P U P U P U P U V P U V P P U 7 P U P U P U P U U P U P U P U 8 U U U U U U U U 40 A Guide to Nestling Development and Aging in Altricial Passerines Chestnut-collared Longspur (Calcarius ornatus) continued Day 1 Key Visual Indicators: - Down may appear wet or clumped together - Eyes closed - Nestling may be curled into a ball Feather Tract Development Tract N V P U F n Capital 100 8 Dorsal 100 8 Humeral 100 8 Alar 100 8 Femoral 100 8 Crural 100 8 Caudal 100 8 Ventral 88 12 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 2.12 ± 0.41 1.7 2.8 9 Tarsus 6.75 ± 0.67 5.93 7.94 9 Wing Chord 5.78 ± 0.87 4.5 7.0 9 Culmen 2.29 ± 0.14 2.1 2.5 9 Outer Primary 0 0 0 10 Outer Rectrix 0 0 0 10 Longest Broken Primary 0 0 0 10 Length 35.0 ± 1.91 33.0 38.0 7 Gape 7.92 ± 0.74 6.85 8.9 7 General Description Eyes and ears are closed. Skin and legs flesh colored with orange tinge (salmon). All feather tracts are usually not visible though areas around feather tracts may appear slightly darker or as stippling of skin surface. Skin lighter on ventral side and legs. Light grey/tan down on all feather tracts except ventral. Down approx. 5 mm long and may be wet or clumped together. Pale bill with white rictus. Ear canal appears as a shallow indentation. May display weak, shaky gaping and weak forward movement. Can’t hold head up. Lays flat on belly or may curl into ball shape. Very rarely makes very soft chirping sound, most made no noise. Day 2 Key Visual Indicators: - Some feather tracts (alar, dorsal, and ventral) becoming visible as darker areas or very small dark spots Feather Tract Development Tract N V P U F n Capital 100 10 Dorsal 60 40 10 Humeral 100 10 Alar 50 50 10 Femoral 100 10 Crural 100 10 Caudal 100 10 Ventral 40 60 10 Morphometric Data Measurements Mean ± SD Min Max n Weight 3.16 ± 0.78 1.9 4.7 10 Tarsus 7.90 ± 0.69 6.62 8.91 10 Wing Chord 6.96 ± 1.34 4.9 9.0 8 Culmen 2.50 ± 0.29 1.82 2.8 9 Outer Primary 0 0 0 9 Outer Rectrix 0 0 0 10 Longest Broken Primary 0 0 0 10 Length 38.7 ± 1.83 37.0 43.0 10 Gape 8.66 ± 0.69 7.4 9.77 10 General Description Appearance very much the same as first day except that skin appears slightly darker and some pins are becoming visible. Subcutaneous alar pins are becoming visible. Dorsal tract may be visible as darker area or very small dark spots. Ventral pins not pigmented. Position and movement the same as day one. Can’t hold head up and may still curl into ball shape. Results 41 Day 3 Key Visual Indicators: - Dorsal and capital tracts becoming darker (gray) - Pins may be emerging on alar tract Feather Tract Development Tract N V P U F n Capital 15 85 13 Dorsal 8 92 13 Humeral 31 69 13 Alar 15 54 31 13 Femoral 31 69 13 Crural 54 46 13 Caudal 77 23 13 Ventral 92 8 13 Morphometric Data Measurements Mean ± SD Min Max n Weight 4.49 ± 0.84 2.6 5.9 13 Tarsus 9.51 ± 1.05 6.89 11.19 13 Wing Chord 8.3 ± 1.10 6.5 10.3 13 Culmen 2.90 ± 0.34 2.25 3.4 13 Outer Primary 0.25 ± 0.45 0 1.0 12 Outer Rectrix 0 0 0 13 Longest Broken Primary 0 0 0 13 Length 43.45 ± 2.34 39.0 48.0 11 Gape 9.82 ± 0.71 8.19 10.93 13 General Description Eyes are closed. Ear canal is larger. Skin less orange and darker overall with dark gray areas at feather tracts. Pins may be emerging on alar tracts. Dorsal and capital tracts becoming darker gray. Dorsal tract forms a dark gray stripe along back. Ventral tract is clearly visible and may be pressing up on skin. Gape orange-red with white rictus. May be gaping at noises and holds head up for a few seconds. Movement weak but steadier. Can right itself with some effort. Quiet. Chestnut-collared Longspur (Calcarius ornatus) continued Day 4 Key Visual Indicators: - Eyes begin to open - Most feather tracts visible - Alar pins have typically emerged 1-2 mm Feather Tract Development Tract N V P U F n Capital 9 91 11 Dorsal 54 45 11 Humeral 9 55 36 11 Alar 18 82 11 Femoral 64 36 11 Crural 28 36 36 11 Caudal 27 64 9 11 Ventral 64 36 11 Morphometric Data Measurements Mean ± SD Min Max n Weight 6.43 ± 1.31 3.7 8.5 11 Tarsus 11.50 ± 1.37 8.64 13.36 11 Wing Chord 11.5 ± 2.17 9.0 16.0 10 Culmen 3.28 ± 0.34 2.6 3.7 11 Outer Primary 1.56 ± 0.82 0.5 3.0 8 Outer Rectrix 0 0 0 13 Longest Broken Primary 0 0 0 13 Length 48.44 ± 3.32 41.0 53.0 9 Gape 10.81 ± 0.76 9.2 11.81 11 General Description Eyes may be partially open. Ear canal appears open. Skin around dorsal tract appears reddish. Ventral side and legs flesh colored. All feather tracts except caudal are visible and may be pressing up on skin. Alar pins have typically emerged. Still downy on all tracts except ventral; caudal down very sparse or absent. Gaping longer and overall movement is stronger. Rights itself in a few seconds and weakly scoots forward with legs. Some soft noises including soft clicking noises. 42 A Guide to Nestling Development and Aging in Altricial Passerines Day 5 Key Visual Indicators: - Eyes partially to fully open - Pin feathers are typically out on all tracts - Movement is strong and nestling may balance on rump and tarsus Feather Tract Development Tract N V P U F n Capital 8 23 69 13 Dorsal 15 85 13 Humeral 15 85 13 Alar 8 92 13 Femoral 15 85 13 Crural 15 15 70 13 Caudal 8 30 62 13 Ventral 31 69 13 Morphometric Data Measurements Mean ± SD Min Max n Weight 8.88 ± 1.29 6.2 11.2 13 Tarsus 14.09 ± 1.21 12.26 15.77 13 Wing Chord 16.27 ± 2.57 11.0 21.5 13 Culmen 3.74 ± 0.23 3.38 4.1 13 Outer Primary 3.95 ± 2.31 1.5 9.0 10 Outer Rectrix 0.35 ± 0.55 0 1.5 13 Longest Broken Primary 0 0 0 13 Length 53.91 ± 1.51 51.0 56.0 11 Gape 11.73 ± 0.65 10.3 12.8 13 General Description Eyes at least partially open. Skin appears the same color as day four. Pins are typically emerging on all feather tracts but unsheathing has not yet begun. Down still present but more sparse. More frequent, stronger movement and may balance on rump and tarsus. More frequent and louder chirping noises. Chestnut-collared Longspur (Calcarius ornatus) continued Day 6 Key Visual Indicators: - Pins may be unsheathing on all feather tracts except caudal - Eyes may appear fully open - Primary tips appear pale and ready to unsheathe Feather Tract Development Tract N V P U F n Capital 9 82 9 11 Dorsal 64 36 11 Humeral 55 45 11 Alar 64 36 11 Femoral 36 64 11 Crural 9 64 27 11 Caudal 9 91 11 Ventral 55 45 11 Morphometric Data Measurements Mean ± SD Min Max n Weight 10.18 ± 1.56 7.7 11.7 11 Tarsus 15.76 ± 1.34 12.86 17.33 11 Wing Chord 20.18 ± 2.48 16.0 23.0 11 Culmen 4.03 ± 0.31 3.58 4.6 11 Outer Primary 6.73 ± 1.79 4.0 9.0 11 Outer Rectrix 1.09 ± 0.70 0 2.0 11 Longest Broken Primary 0 0 0 11 Length 58.11 ± 3.22 55.0 66.0 9 Gape 12.37 ± 0.63 11.08 13.13 11 General Description Eyes are fully open. Feathers may be beginning to unsheathe on all tracts except caudal and capital. Tips of primaries appear pale and ready to unsheathe. Tips of wing coverts may appear tan colored if unsheathed. Down still present. Movement is strong, holds head up. Makes chirping noises as well as occasional harsher, louder chips. Results 43 Day 7 Key Visual Indicators: - Primaries may begin to unsheathe - Holds head up almost constantly Feather Tract Development Tract N V P U F n Capital 45 55 9 Dorsal 22 88 9 Humeral 45 55 9 Alar 11 89 9 Femoral 100 9 Crural 22 78 9 Caudal 78 22 9 Ventral 11 89 9 Morphometric Data Measurements Mean ± SD Min Max n Weight 12.01 ± 2.85 7.0 14.7 9 Tarsus 17.76 ± 1.41 15.2 19.69 9 Wing Chord 25.33 ± 4.85 18.0 33.0 9 Culmen 4.39 ± 0.36 3.8 4.9 9 Outer Primary 10.22 ± 2.28 7.0 14.0 9 Outer Rectrix 2.67 ± 1.22 1.0 5.0 9 Longest Broken Primary 0.44 ± 0.53 0 1.0 9 Length 63.71 ± 4.96 58.0 70.0 7 Gape 12.40 ± 0.61 11.33 13.27 9 General Description Sparse down. All feather tracts are typically unsheathing except caudal. Primaries are beginning to unsheathe. Apteria are obscured by pin feathers along back and flanks. Moves more frequently and appears alert. Holds head up almost constantly. Young are typically ready for banding. Chestnut-collared Longspur (Calcarius ornatus) continued Day 8 Key Visual Indicators: - Primaries unsheathing 2-3 mm - All feather tracts are unsheathing Feather Tract Development Tract N V P U F n Capital 100 4 Dorsal 100 4 Humeral 100 4 Alar 100 4 Femoral 100 4 Crural 100 4 Caudal 100 4 Ventral 100 4 Morphometric Data Measurements Mean ± SD Min Max n Weight 14.9 ± 0.90 14 16.1 4 Tarsus 18.98 ± 0.68 18.06 19.65 4 Wing Chord 31.0 ± 3.27 27.0 35.0 4 Culmen 4.52 ± 0.27 4.26 4.8 4 Outer Primary 13.5 ± 2.52 10.0 16.0 4 Outer Rectrix 3.75 ± 0.50 3.0 4.0 4 Longest Broken Primary 2.25 ± 0.96 1.0 3.0 4 Length 67.75 ± 5.91 60.0 74.0 4 Gape 12.48 ± 0.21 12.18 12.68 4 General Description All feather tracts unsheathing. Primaries typically unsheathed 2-3 mm. Unsheathed wing coverts form light tan wing bars. Most feathers out to the extent that sheaths may not be visible under feathers and young appear feathered. More active, controlled movements and chirping noises given. 44 A Guide to Nestling Development and Aging in Altricial Passerines Species Accounts American Goldfinch Cardeulis tristis Data collection: Point Reyes National Seashore, Marin County, California. Nests: n = 4 (2004), n = 2 (2005). Nest Period Data: Average (range), n = number of nests Building: no data Clutch size: 4.9 (4 - 6) eggs, n = 55 Incubation: 11.5 (10 - 17) days, n = 16 Nestling: 13.5 (11 - 16) days, n = 15 Indicator Table: American Goldfinch visual characteristics typical at a given age. Alar pins are very light in color and difficult to see 1 Alar pins are light in color and centered across the dorsal wing surface 2 Dorsal tract is visible as light gray pins 3 Eyes begin to open 4-5 Alar pins have grown to posterior edge of wing and appear ready to emerge 4 Alar pins begin to emerge 5 Contour feather pins begin to emerge 6 Ventral tract has begun to unsheathe 7 Most contour feather tracts have begun to unsheathe 8 Primary pins begin to unsheathe 8-9 Capital tract pins are unsheathing 10 Young appear soft due to extent of unsheathing 11 Young appear very alert and can hop on the ground 11 Indicator characteristics Age Indicator characteristics Age General Feather Development: American Goldfinch feather tract development by day. Most advanced stage is indicated as N-Not visible (not pigmented), V-Visible below skin, P-Pins above skin, U-Unsheathing, or F-Fully unsheathed. Day Capital Dorsal Humeral Alar Femoral Crural Caudal Ventral 1 N N N N V N N N N 2 N N V N V V N N N N 3 N V N V N V V N V N N V N V 4 V V V V V N V N V V 5 V V V P V V V V P 6 V V P V P P V P V P V P V P 7 V P P P P P U V P V P P U 8 P P U P U P U U P U P U U 9 P U U U U U U P U U 10 U U U U U U U U 11 U U U U U U U U 45 Day 1 Key Visual Indicators: - Young are egg size and down may be matted - Alar pins are very light in color and difficult to see - No other pigmented pins are visible Feather Tract Development Tract N V P U F n Capital 100 6 Dorsal 100 6 Humeral 100 6 Alar 33 67 6 Femoral 100 6 Crural 100 6 Caudal 100 6 Ventral 100 6 Morphometric Data Measurements Mean ± SD Min Max n Weight 1.23 ± 0.288 0.8 1.6 6 Tarsus 4.34 ± 0.214 4.13 4.67 6 Wing Chord 4.0 ± 0.316 3.5 4.5 6 Culmen 2.08 ± 0.117 1.91 2.21 6 Outer Primary 0 0 0 6 Outer Rectrix 0 0 0 6 Longest Broken Primary 0 0 0 6 Length 29.08 ± 2.764 25.5 33 6 Gape 5.64 ± 0.297 5.15 5.97 6 General Description Eyes are closed. Ear is closed and visible as an indentation. Bill is yellow-orange with a violet-pink gape. Light colored down is present on the capital, dorsal, humeral, alar, femoral, and crural tracts and may be matted. Alar pins may be visible but are very light in color. No other feather tracts are visible. Young are egg size and weigh less than 2 grams. American Goldfinch (Cardeulis tristis) continued Day 2 Key Visual Indicators: - Alar pins are light in color and centered across the dorsal surface of wing - No other feather tracts are readily apparent Feather Tract Development Tract N V P U F n Capital 100 8 Dorsal 75 25 8 Humeral 87.5 12.5 8 Alar 100 8 Femoral 100 8 Crural 100 8 Caudal 100 8 Ventral 100 7 Morphometric Data Measurements Mean ± SD Min Max n Weight 2.05 ± 0.307 1.6 2.5 8 Tarsus 5.25 ± 0.406 4.6 5.72 8 Wing Chord 4.69 ± 0.372 0 5.0 8 Culmen 2.39 ± 0.076 2.32 2.52 8 Outer Primary 0 0 0 8 Outer Rectrix 0 0 0 8 Longest Broken Primary 0 0 0 8 Length 32.88 ± 2.031 31.0 36.0 8 Gape 6.55 ± 0.422 6.01 7.22 8 General Description Eyes are closed. Alar pins are visible as very light pins centered across the dorsal surface of wing. Ventral tract is not pigmented but appears as stippling on skin surface. No other tracts are visible. Results 46 A Guide to Nestling Development and Aging in Altricial Passerines Day 3 Key Visual Indicators: - Alar pins have grown towards posterior edge of wing - Dorsal tract is visible as very light gray pins - Skin around head and dorsal surface begins to darken Feather Tract Development Tract N V P U F n Capital 80 20 10 Dorsal 10 90 10 Humeral 50 50 10 Alar 100 10 Femoral 60 40 10 Crural 100 10 Caudal 60 40 10 Ventral 70 30 10 Morphometric Data Measurements Mean ± SD Min Max n Weight 2.58 ± 0.437 1.6 3 8 Tarsus 7.01 ± 1.026 5.92 8.94 10 Wing Chord 5.2 ± 1.033 3.0 6.0 10 Culmen 2.76 ± 0.127 2.55 2.99 10 Outer Primary 0 0 0 10 Outer Rectrix 0 0 0 10 Longest Broken Primary 0 0 0 10 Length 36.9 ± 2.283 32.0 40.0 10 Gape 7.08 ± 0.409 6.48 7.56 10 General Description Eyes closed. Alar pins have grown towards posterior edge of wing. Dorsal tract is visible as light gray pins. Humeral tract may be visible. Caudal tract may just be visible. Ventral tract is visible as unpigmented stippling. Abdomen is enlarged and darkening. American Goldfinch (Cardeulis tristis) continued Day 4 Key Visual Indicators: - Alar pins have grown to the posterior edge of wing and appear ready to emerge - Hair-like projections appear where alar pins will emerge Feather Tract Development Tract N V P U F n Capital 100 6 Dorsal 100 6 Humeral 100 6 Alar 100 6 Femoral 100 6 Crural 67 33 6 Caudal 17 83 6 Ventral 100 6 Morphometric Data Measurements Mean ± SD Min Max n Weight 3.54 ± 0.688 2.4 4.1 5 Tarsus 8.95 ± 0.830 7.44 9.85 6 Wing Chord 6.92 ± 0.970 5.0 7.5 6 Culmen 3.11 ± 0.111 2.92 3.24 6 Outer Primary 0 0 0 6 Outer Rectrix 0 0 0 6 Longest Broken Primary 0 0 0 6 Length 41.67 ± 2.875 37.0 45.0 6 Gape 8.03 ± 0.654 6.74 8.51 6 General Description Eyes may be partially opened. Ear canal may be partially open. Capital tract is just becoming visible and area is darkening. Dorsal tract area is darkening. Alar pins have grown to the edge of wing and appear ready to emerge. Hair-like projections appear where alar pins will emerge. Humeral tract visible as gray flecks. Ventral tract visible as gray flecks near the chest and as flesh colored stippling across the sides of the abdomen. Results 47 Day 5 Key Visual Indicators: - Alar tract pins have emerged or just emerged - Capital, dorsal, and humeral tracts are dark, but no pins have emerged Feather Tract Development Tract N V P U F n Capital 100 8 Dorsal 100 8 Humeral 100 8 Alar 100 8 Femoral 100 8 Crural 100 8 Caudal 100 8 Ventral 87.5 12.5 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 5.11 ± 0.582 4.4 6.2 8 Tarsus 10.19 ± 1.288 8.43 12.12 8 Wing Chord 11.38 ± 1.706 8.0 14.0 8 Culmen 3.55 ± 0.088 3.34 3.63 8 Outer Primary 0.94 ± 0.417 0.5 1.5 8 Outer Rectrix 0 0 0 8 Longest Broken Primary 0 0 0 8 Length 45.38 ± 3.114 41.0 51.0 8 Gape 8.49 ± 0.295 8.13 8.99 8 General Description Eyes are partially open. Capital tract is dark. Dorsal tract is dark and appears as a gray strip along the spine. Humeral and femoral tracts visible as a gray strip. Some alar pins have emerged. Crural tract visible as a few gray flecks. Seed stored in crop may be apparent. American Goldfinch (Cardeulis tristis) continued Day 6 Key Visual Indicators: - Alar pins are 2-3mm in length - Most contour feather pins have just emerged or have tips pressing up on skin surface Feather Tract Development Tract N V P U F n Capital 100 10 Dorsal 30 70 10 Humeral 30 70 10 Alar 100 10 Femoral 30 70 10 Crural 90 10 10 Caudal 90 10 10 Ventral 30 70 10 Morphometric Data Measurements Mean ± SD Min Max n Weight 6.09 ± 0.723 4.4 7.1 10 Tarsus 11.60 ± 0.774 10.37 12.96 10 Wing Chord 15.15 ± 1.717 11.0 17.0 10 Culmen 3.85 ± 0.199 3.45 4.15 10 Outer Primary 2.85 ± 0.883 0.5 3.5 10 Outer Rectrix 0.05 ± 0.158 0 0.5 10 Longest Broken Primary 0 0 0 10 Length 48.35 ± 3.496 41.0 54.0 10 Gape 8.82 ± 0.288 8.34 9.22 10 General Description Dorsal, humeral, femoral, and ventral tracts have darkened and are just emerging. Primary, secondary, and some covert alar pins have emerged. Alar pins have emerged 2-3mm. Femoral pins have lengthened and may have emerged. Hair-like projections appear where caudal pins will emerge. 48 A Guide to Nestling Development and Aging in Altricial Passerines Day 7 Key Visual Indicators: - Dorsal, humeral, and caudal tracts have emerged by 1-2 mm - Ventral tract has just begun to unsheathe Feather Tract Development Tract N V P U F n Capital 87.5 12.5 8 Dorsal 100 8 Humeral 100 8 Alar 100 8 Femoral 75 25 8 Crural 12.5 87.5 8 Caudal 12.5 87.5 8 Ventral 37.5 62.5 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 7.03 ± 0.634 5.8 7.8 8 Tarsus 13.09 ± 0.731 12.27 14.64 8 Wing Chord 19.19 ± 1.963 15.0 21.5 8 Culmen 4.10 ± 0.156 3.76 4.25 8 Outer Primary 5.5 ± 1.282 2.5 6.5 8 Outer Rectrix 0.688 ± 0.372 0 1.0 8 Longest Broken Primary 0 0 0 8 Length 51.13 ± 4.581 42.0 58.0 8 Gape 8.99 ± 0.582 7.91 9.59 8 General Description Eyes appear fully open. Capital tract pushing up on skin. All other tracts have emerged. Dorsal and humeral tract pins are out 1-2 mm. Ventral pins are typically unsheathing. Caudal pins are just emerged. American Goldfinch (Cardeulis tristis) continued Day 8 Key Visual Indicators: - Some wing coverts have begun to unsheathe - Capital tract pins have typically begun to emerge - Most contour feather tracts have begun to un sheathe Feather Tract Development Tract N V P U F n Capital 100 10 Dorsal 10 90 10 Humeral 10 90 10 Alar 20 80 10 Femoral 100 10 Crural 10 90 10 Caudal 80 20 10 Ventral 100 10 Morphometric Data Measurements Mean ± SD Min Max n Weight 8.34 ± 0.938 6.2 9.8 10 Tarsus 13.19 ± 0.721 11.96 14.23 10 Wing Chord 23.65 ± 2.310 18.0 26.0 10 Culmen 4.48 ± 0.201 4.19 4.87 10 Outer Primary 8.7 ± 1.418 5.0 10.0 10 Outer Rectrix 1.95 ± 0.762 0.5 3.0 10 Longest Broken Primary 0.25 ± 0.354 0 1.0 10 Length 55.5 ± 3.274 48.0 59.0 10 Gape 9.17 ± 0.650 8.01 9.95 10 General Description Capital tract pins have emerged. Some dorsal, humeral, femoral, and crural tract pins unsheathing. Some wing coverts unsheathing. Primary and secondary pin tips appear white and ready to unsheathe or have just begun to unsheathe. Most ventral tract pins are unsheathing. Young can stand up on tarsus. Young are typically ready for banding. Results 49 Day 9 Key Visual Indicators: - Most primary pins have begun to unsheathe - Most contour feather pins (except capital) are un sheathing at tips Feather Tract Development Tract N V P U F n Capital 50 50 8 Dorsal 100 8 Humeral 100 8 Alar 100 8 Femoral 100 8 Crural 100 8 Caudal 12.5 87.5 8 Ventral 100 8 Morphometric Data Measurements Mean ± SD Min Max n Weight 9.09 ± 0.869 7.5 10.2 8 Tarsus 14.15 ± 0.669 13.54 15.19 7 Wing Chord 26.19 ± 2.137 22.0 29.0 8 Culmen 4.64 ± 0.180 4.3 4.91 8 Outer Primary 11.69 ± 1.624 8.0 13.0 8 Outer Rectrix 3.63 ± 1.188 1.0 5.0 8 Longest Broken Primary 1.56 ± 0.729 0 2.0 8 Length 57.25 ± 3.775 52.0 60.0 4 Gape 9.36 ± 0.447 8.94 10.14 8 General Description Capital tract pins may be unsheathing. Most dorsal, humeral, crural, and femoral pins are unsheathing and have light cinnamon tips. Alar pins unsheathed 1-2 mm. Caudal pins have begun to unsheathe. Young appear alert. America |
| Original Filename | altricialpasserines07.pdf |
| Images Source File Name | 6700.pdf |
| Date created | 2012-12-13 |
| Date modified | 2014-11-05 |
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