Distribution and derivation of the Blue-winged Teal (Anas discors) harvest, 1970–2003.

              U.S. Fish & Wildlife Service
Distribution and
Derivation of the
Blue-winged Teal
(Anas discors) Harvest,
1970 – 2003
Biological Technical Publication
BTP-R6017-2013
Photo by Craig Bihrle
i
U.S. Fish & Wildlife Service
Distribution and
Derivation of the
Blue-winged Teal
(Anas discors) Harvest,
1970 – 2003
Biological Technical Publication
BTP-R6017-2013
Michael L. Szymanski 1
James A. Dubovsky 2
1 North Dakota Game and Fish Department, Bismarck, ND
2 U. S. Fish and Wildlife Service, Division of Migratory Bird Management,
Denver, CO
Cover image: Blue-winged Teal
Photo credit: Craig Bihrle, North Dakota Game and Fish Department
ii Distribution and Derivation of the Blue-winged Teal Harvest
Author Contact Information:
Michael L. Szymanski
North Dakota Game and Fish Department
Migratory Game Bird Biologist
100 N. Bismarck Expressway
Bismarck, ND 58501
Phone: (701) 328-6360
Email: mszymanski@nd.gov
James A. Dubovsky
U.S. Fish and Wildlife Service
Central Flyway Representative
Division of Migratory Bird Management
755 Parfet Street, Suite 235
Lakewood, CO 80215
Phone: (303) 275-2386
E-mail: james_dubovsky@fws.gov
Recommended citation:
Szymanski, M. L., and J. A. Dubovsky. 2013. Dis-tribution
and derivation of the Blue-winged Teal
(Anas discors) harvest, 1970–2003. U.S. Depart-ment
of Interior, Fish and Wildlife Service, Biologi-cal
Technical Publication FWS/BTP-R6017-2013,
Washington, D.C.
For additional copies or information, contact:
Michael L. Szymanski
North Dakota Game and Fish Department
Migratory Game Bird Biologist
100 N. Bismarck Expressway
Bismarck, ND 58501
Phone: (701) 328-6360
Email: mszymanski@nd.gov
Series Senior Technical Editor:
Stephanie L. Jones
U.S. Fish and Wildlife Service
Region 6 Nongame Migratory Bird Coordinator
P.O. Box 25486-DFC
Denver, CO 80225-0486
ISSN 2160-9498 Electronic ISSN 2160-9497
Biological Technical Publications online: http://library.fws.gov/BiologicalTechnicalPublications.html
Table of Contents iii
Table of Contents
List of Figures .......................................................................................................................................................vii
List of Tables .........................................................................................................................................................xi
Acknowledgments .............................................................................................................................................. xii
Executive Summary ........................................................................................................................................... xiii
Introduction ........................................................................................................................................................... 1
Objectives .............................................................................................................................................................. 4
Methods ................................................................................................................................................................. 5
Datasets Used ..................................................................................................................................................... 5
	
Breeding population data............................................................................................................................... 5
Banding and band recovery data ................................................................................................................... 5
Harvest data ..................................................................................................................................................... 5
Development of Breeding Reference Areas .................................................................................................... 6
Development of Harvest Areas ......................................................................................................................... 6
Calculation of Distribution and Derivation of the Harvest ............................................................................ 6
Recovery weights................................................................................................................................................ 8
Pooling data among years ............................................................................................................................... 8
Band-reporting rates ....................................................................................................................................... 8
Estimation of the age and sex structure of the preseason population ........................................................9
Spatial Analysis of Recoveries ...........................................................................................................................10
Results and Discussion ........................................................................................................................................11
Breeding Reference Areas and Harvest Areas................................................................................................11
Recovery Weight Components............................................................................................................................11
Composite reporting rates...............................................................................................................................12
Harvest rates.......................................................................................................................................................13
Preseason population structure......................................................................................................................13
Band recovery rates.........................................................................................................................................14
Distribution and Relative Density of the Blue-winged Teal Harvest from Breeding Reference Areas
	
to Major and Minor Harvest Areas, 1970 – 2003.............................................................................................14
All age/sex classes............................................................................................................................................14
Breeding reference areas west of 87°W..........................................................................................................14
Central Alberta BRA....................................................................................................................................14
Southern Alberta BRA.................................................................................................................................14
Western Saskatchewan BRA........................................................................................................................14
iv Distribution and Derivation of the Blue-winged Teal Harvest
Eastern Saskatchewan/Southwest Manitoba BRA..................................................................................14
West-central Manitoba BRA........................................................................................................................20
Northern Great Plains BRA....................................................................................................................... 20
Eastern Dakotas BRA................................................................................................................................ 23
Upper Midwest BRA................................................................................................................................... 23
Breeding reference areas east of 87°W.......................................................................................................... 23
U.S. Great Lakes BRA................................................................................................................................ 23
Eastern Ontario/Southern Quebec BRA......................................................................................................... 23
Maritimes/Maine BRA............................................................................................................................... 23
Northeast States BRA..................................................................................................................................23
All breeding reference areas by age/sex class............................................................................................. 23
Adult males................................................................................................................................................... 23
Adult females................................................................................................................................................ 23
Immature males........................................................................................................................................... 23
Immature females....................................................................................................................................... 23
Derivation of the Blue-winged Teal Harvest from Breeding Reference Areas, 1970 – 2003.................... 30
All age/sex classes........................................................................................................................................... 30
Canada.............................................................................................................................................................. 30
Alberta........................................................................................................................................................... 30
Saskatchewan............................................................................................................................................... 30
Manitoba....................................................................................................................................................... 31
Ontario................................................................................................................................................................ 31
Quebec........................................................................................................................................................... 31
Maritimes Provinces.................................................................................................................................. 31
Pacific Flyway................................................................................................................................................... 31
Pacific Flyway – North............................................................................................................................... 39
Pacific Flyway – South............................................................................................................................... 39
Central Flyway................................................................................................................................................ 39
Central Flyway High Plains – North........................................................................................................ 39
Central Flyway Low Plains – North.......................................................................................................... 39
Central Flyway High Plains – South.............................................................................................................. 39
Central Flyway Low Plains – South......................................................................................................... 39
Mississippi Flyway.......................................................................................................................................... 39
Mississippi Flyway – Northwest............................................................................................................... 39
Mississippi Flyway – Northeast................................................................................................................ 39
Mississippi Flyway – West-central.................................................................................................................. 39
Mississippi Flyway – South....................................................................................................................... 39
Mississippi Flyway – Gulf Coast............................................................................................................... 39
Atlantic Flyway................................................................................................................................................ 39
Atlantic Flyway – North............................................................................................................................ 39
Atlantic Flyway – Central.......................................................................................................................... 39
Atlantic Flyway – South............................................................................................................................. 39
Latin America.................................................................................................................................................. 39
Mexico.............................................................................................................................................................39
Central America........................................................................................................................................... 39
South America.............................................................................................................................................. 39
Name of Section v
Caribbean Countries.................................................................................................................................... 39
All harvest areas by age/sex class.................................................................................................................. 49
Adult males................................................................................................................................................... 49
Adult females................................................................................................................................................ 49
Immature males........................................................................................................................................... 49
Immature females........................................................................................................................................ 49
Changes in Distribution of the Blue-winged Teal Harvest between Time Periods.................................... 49
Changes in Derivation of the Blue-winged Teal Harvest between Time Periods...................................... 49
Grouping Breeding Reference Areas for Future Analyses........................................................................... 54
Bi-weekly Harvest of Blue-winged Teal.......................................................................................................... 55
Management Implications................................................................................................................................... 57
Literature Cited..................................................................................................................................................... 58
Appendix A. Numbers of Blue-winged Teal banded and direct recoveries by breeding reference area,
time period, and age/sex class.......................................................................................................................... 60
Appendix B. Average annual harvest rates of Blue-winged Teal by breeding reference area,
	
time period, and age/sex class.......................................................................................................................... 62
Appendix C. Blue-winged Teal recovery weights by breeding reference area,
	
time period and age/sex class........................................................................................................................... 63
Appendix D. Distribution of the Blue-winged Teal harvest for all age/sex classes, 1970 – 1979.............. 65
Appendix E. Distribution of the Blue-winged Teal harvest for all age/sex classes, 1980 – 1986............... 66
Appendix F. Distribution of the Blue-winged Teal harvest for all age/sex classes, 1987 – 1993................ 67
Appendix G. Distribution of the Blue-winged Teal harvest for all age/sex classes, 1994 – 2003............... 68
Appendix H. Derivation of the Blue-winged Teal harvest for all age/sex classes, 1970 – 1979.................. 69
Appendix I. Derivation of the Blue-winged Teal harvest for all age/sex classes, 1980 – 1986................... 70
Appendix J. Derivation of the Blue-winged Teal harvest for all age/sex classes, 1987 – 1993.................. 71
Appendix K. Derivation of the Blue-winged Teal harvest for all age/sex classes, 1994 – 2003.................. 72
Appendix L. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 1,242) of all age/sex classes, 1 – 14 September, 1970 – 2003................................................................. 73
Appendix M. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 4,092) of all age/sex classes, 15 – 28 September, 1970 – 2003............................................................... 73
Appendix N. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 3,546) of all age/sex classes, 29 September – 12 October, 1970 – 2003................................................ 74
Appendix O. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 856) of all age/sex classes, 13 October – 26 October, 1970 – 2003........................................................ 74
Appendix P. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 520) of all age/sex classes, 27 October – 9 November, 1970 – 2003..................................................... 75
Table of Contents vi Distribution and Derivation of the Blue-winged Teal Harvest
Appendix Q. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 825) of all age/sex classes, 10 November – 23 November, 1970 – 2003............................................... 75
Appendix R. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 552) of all age/sex classes, 24 November – 7 December, 1970 – 2003.................................................. 76
Appendix S. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 410) of all age/sex classes, 8 December – 21 December, 1970 – 2003.................................................. 76
Appendix T. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 521) of all age/sex classes, 22 December – 4 January, 1970 – 2003...................................................... 77
Appendix U. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 469) of all age/sex classes, 5 January – 18 January, 1970 – 2003.......................................................... 77
Appendix V. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 201) of all age/sex classes, 19 January – 1 February, 1970 – 2003....................................................... 78
Appendix W. Relative harvest density of Blue-winged Teal derived from direct recoveries
	
(n = 167) of all age/sex classes, 2 February – 29 March, 1970 – 2003.......................................................... 78
List of Figures
Figure 1. Breeding and wintering ranges for Blue-winged Teal (Anas discors; adapted from Bellrose 1980,
Rowher et al. 2002) ...................................................................................................................................................... 1
Figure 2. Strata and transects for the Waterfowl Breeding Population and Habitat Survey (yellow =
traditional survey area, green = eastern survey area; U.S. Fish and Wildlife Service 2009). .......................... 2
Figure 3. Blue-winged Teal harvests, 1970 – 2003 (Kruse et al. 2002, Gendron and Collins 2007, Kruse 2009).
Latin American harvests (H) for each age/sex class are based on:
	
HLatin American Area, age/sex class = [(HU.S., age/sex class + HCanada, age/sex class) / (1 – ρage/sex class)] - (HU.S., age/sexc lass +
	
HCanada, age/sex class) ..................................................................................................................................................... 3
Figure 4. Blue-winged Teal breeding population indices from the Waterfowl Breeding Population and
Habitat Survey area (Smith 1995, U.S. Fish and Wildlife Service 2009), and all breeding areas. The
Traditional area is represented by strata 1 – 18, 20 – 50, and 75 – 77 (U.S. Fish and Wildlife Service 2009).
Data for All Areas includes survey data from state surveys and beginning in 1990, from the Eastern Survey
Area (strata 51 – 72; U.S. Fish and Wildlife Service 2009). Prior to 1990, breeding population indices in
eastern breeding areas were based on their proportional contribution to the overall breeding population
index in years where data was available. ................................................................................................................... 4
Figure 5. Least squares means of principal component 1 vs. least squares means of principal component
2 derived from recovery latitude, longitude, and log-transformed recovery date of Blue-winged Teal (n
= 23,279) by their breeding population strata of the Waterfowl Breeding Population and Habitat Survey
(U.S. Fish and Wildlife Service 2009). States or regions treated as strata were given unique numbers
(200 = Minnesota, 201 = Iowa, 202 = Wisconsin, 203 = Michigan, 204 = Ohio, 207 = Pennsylvania, 208
= Maryland, 209 = Delaware, 300 = New York, 301 = Vermont, 304 = Massachusetts, and 307 = Gaspe
Peninsula region of Quebec). ...................................................................................................................................... 7
Figure 6. Least squares means of principal component 1 vs. least squares means of principal component 2
derived from recovery latitude, longitude, and log-transformed recovery date of Blue-winged Teal (n = 23,279)
by their breeding population strata of the Waterfowl Breeding Population and Habitat Survey (U.S. Fish and
Wildlife Service 2009), after grouping into breeding reference areas (BRAs; 1 = Central Alberta, 2 = Southern
Alberta, 3 = Western Saskatchewan, 4 = Eastern Saskatchewan/Southwest Manitoba, 5 = Westcentral
Manitoba, 6 = Northern Great Plains, 7 = Eastern Dakotas, 8 = Upper Midwest, 9 = U.S. Great Lakes, 10 =
Eastern Ontario/Southern Quebec, 11 = Maritimes/Maine, and 12 = Northeast States) ..................................... 7
Figure 7. May pond counts in North Dakota, 1974 – 2008, from the North Dakota Game and Fish Breeding
Duck Survey (M. A. Johnson, pers. comm.) and the Waterfowl Breeding Population and Habitat Survey
(Strata 41 – 49; Smith 1995, U.S. Fish and Wildlife Service 2009) used to estimate numbers of ponds in the
north-central U.S. prior to 1974. ............................................................................................................................... 8
Figure 8. Average numbers (± 95% CL) of May ponds in Prairie Canada (Strata 25 – 40) and North-central
U.S. (strata 41 – 49) from the Waterfowl Breeding Population and Habitat Survey (Smith 1995, U.S. Fish
and Wildlife Service 2009) by time period. ............................................................................................................... 8
Figure 9. Composite band-reporting rates for Blue-winged Teal by breeding reference area and time
period. Composite band-reporting rates are the weighted average of reporting rates for different reporting
methods used to report recoveries ..................................................................................................................... 10
List of Figures vii
viii Distribution and Derivation of the Blue-winged Teal Harvest
Figure 10. Map showing breeding reference areas for Blue-winged Teal. Breeding reference areas are
geographically aggregated portions of the population that have similar band-recovery distributions. ........ 11
Figure 11. Map showing minor harvest areas for Blue-winged Teal. Minor harvest areas are based on harvest
jurisdictions such as states, or portions of Flyways (PF = Pacific Flyway, CF = Central Flyway, MF = Mississippi
Flyway, AF = Atlantic Flyway). Flyways are aggregations of states, parts of states, and provinces and are the
delivery mechanism for harvest management. Only U.S. portions of Flyways are used and Canadian portions are
described separately. .................................................................................................................................................. 12
Figure 12. Relative harvest density derived from direct recoveries (n = 15,099) of Blue-winged Teal from all
breeding reference areas and all sex/age classes, 1970 – 2003 ............................................................................. 15
Figure 13. Relative harvest density derived from direct recoveries (n = 11,254) of Blue-winged Teal banded
in breeding reference areas west of 87°W for all age/sex classes, 1970 – 2003). ................................................ 15
Figure 14. Distribution of the Blue-winged Teal harvest based on direct recoveries (n = 756), from the
Central Alberta Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003. ............................... 16
Figure 15. Relative harvest density derived from direct recoveries (n = 756) of Blue-winged Teal banded in
the Central Alberta Breeding Reference Area for all age/sex classes, 1970 – 2003 .......................................... 16
Figure 16. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 819), from the
Southern Alberta Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003 ............................. 17
Figure 17. Relative harvest density derived from direct recoveries (n = 819) of Blue-winged Teal banded in
the Southern Alberta Breeding Reference Area for all age/sex classes, 1970 – 2003. ...................................... 17
Figure 18. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,140), from the
Western Saskatchewan Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003 ................... 18
Figure 19. Relative harvest density derived from direct recoveries (n = 1,140) of Blue-winged Teal banded in
the Western Saskatchewan Breeding Reference Area for all age/sex classes, 1970 – 2003.............................. 18
Figure 20. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 3,168), from the
Eastern Saskatchewan/Southwest Manitoba Breeding Reference Area (shaded) for all age/sex classes,
1970 – 2003. ................................................................................................................................................................ 19
Figure 21. Relative harvest density derived from direct recoveries (n = 3,168) of Blue-winged Teal banded in
the Eastern Saskatchewan/Southwest Manitoba Breeding Reference Area for all age/sex classes,
1970 – 2003 ................................................................................................................................................................. 19
Figure 22. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,802), from the
West-central Manitoba Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003. ................... 21
Figure 23. Relative harvest density derived from direct recoveries (n = 1,802) of Blue-winged Teal banded in
the West-central Manitoba Breeding Reference Area for all age/sex classes, 1970 – 2003. ............................ 21
Figure 24. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 815), from the
Northern Great Plains Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003..................... 22
Figure 25. Relative harvest density derived from direct recoveries (n = 815) of Blue-winged Teal banded in
the Northern Great Plains Breeding Reference Area for all age/sex classes, 1970 – 2003............................... 22
Figure 26. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,852), from the
Eastern Dakotas Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003................................ 24
Figure 27. Relative harvest density derived from direct recoveries (n = 1,852) of Blue-winged Teal banded in
the Eastern Dakotas Breeding Reference Area for all age/sex classes, 1970 – 2003. ....................................... 24
Figure 28. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 902), from the
Upper Midwest Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003 ................................. 25
Figure 29. Relative harvest density derived from direct recoveries (n = 902) of Blue-winged Teal banded in
the Upper Midwest Breeding Reference Area for all age/sex classes, 1970 – 2003 .......................................... 25
Figure 30. Relative harvest density derived from direct recoveries (n = 3,845) of Blue-winged Teal banded in
breeding reference areas east of 87°W for all age/sex classes, 1970 – 2003. ....................................................... 26
Figure 31. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,033), from the
U.S. Great Lakes Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003. ............................. 26
Figure 32. Relative harvest density derived from direct recoveries (n = 1,033) of Blue-winged Teal banded in
the U.S. Great Lakes Breeding Reference Area for all age/sex classes, 1970 – 2003 ........................................ 27
Figure 33. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,093), from the
Eastern Ontario/Southern Quebec Breeding Reference Area (shaded) for all age/sex classes,
1970 – 2003 ................................................................................................................................................................... 27
Figure 34. Relative harvest density derived from direct recoveries (n = 1,093) of Blue-winged Teal banded in
the Eastern Ontario/Southern Quebec Breeding Reference Area for all age/sex classes, 1970 – 2003. ......... 28
Figure 35. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,127), from the
Maritimes/Maine Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003 .............................. 28
Figure 36. Relative harvest density derived from direct recoveries (n = 1,127) of Blue-winged Teal banded in
the Maritimes/Maine Breeding Reference Area for all age/sex classes, 1970 – 2003.......................................... 29
Figure 37. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 592), from the
Northeast States Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003. .............................. 29
Figure 38. Relative harvest density derived from direct recoveries (n = 592) of Blue-winged Teal banded in
the Northeast States Breeding Reference Area for all age/sex classes, 1970 – 2003 ........................................ 30
Figure 39. Derivation of Blue-winged Teal harvested in Alberta (shaded) based on direct recoveries
	
(n = 140) of all age/sex classes, 1970 – 2003. ........................................................................................................... 36
Figure 40. Derivation of Blue-winged Teal harvested in Saskatchewan (shaded) based on direct recoveries
	
(n = 162) of all age/sex classes, 1970 – 2003 ............................................................................................................ 36
Figure 41. Derivation of Blue-winged Teal harvested in Manitoba (shaded) based on direct recoveries
	
(n = 236) of all age/sex classes, 1970 – 2003............................................................................................................. 37
Figure 42. Derivation of Blue-winged Teal harvested in Ontario (shaded) based on direct recoveries
	
(n = 1,114) of all age/sex classes, 1970 – 2003.......................................................................................................... 37
Figure 43. Derivation of Blue-winged Teal harvested in Quebec (shaded) based on direct recoveries (n = 536)
of all age/sex classes, 1970 – 2003........................................................................................................................... 38
Figure 44. Derivation of Blue-winged Teal harvested in the Maritimes (shaded) based on direct recoveries
	
(n = 613) of all age/sex classes, 1970 – 2003. ............................................................................................................ 38
List of Figures ix
x Distribution and Derivation of the Blue-winged Teal Harvest
Figure 45. Derivation of Blue-winged Teal harvested in the northern Pacific Flyway (shaded) based on direct
recoveries (n = 11) of all age/sex classes, 1970 – 2003 ........................................................................................... 40
Figure 46. Derivation of Blue-winged Teal harvested in the southern Pacific Flyway (shaded) based on direct
recoveries (n = 68) of all age/sex classes, 1970 – 2003 ........................................................................................... 40
Figure 47. Derivation of Blue-winged Teal harvested in the northern portion of the Central Flyway High
Plains Unit (shaded) based on direct recoveries (n = 84) of all age/sex classes, 1970 – 2003). ........................ 41
Figure 48. Derivation of Blue-winged Teal harvested in the northern portion of the Central Flyway Low
Plains Unit (shaded) based on direct recoveries (n = 360) of all age/sex classes, 1970 – 2003. ........................ 41
Figure 49. Derivation of Blue-winged Teal harvested in the southern portion of the Central Flyway High
Plains Unit (shaded) based on direct recoveries (n = 147) of all age/sex classes, 1970 – 2003 ........................ 42
Figure 50. Derivation of Blue-winged Teal harvested in the southern portion of the Central Flyway High
Plains Unit (shaded) based on direct recoveries (n = 1,732) of age/sex classes, 1970 – 2003 ........................... 42
Figure 51. Derivation of Blue-winged Teal harvested in the northwest portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 2,236) of all age/sex classes, 1970 – 2003. .......................................... 43
Figure 52. Derivation of Blue-winged Teal harvested in the northeast portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 393) of all age/sex classes, 1970 – 2003 .............................................. 43
Figure 53. Derivation of Blue-winged Teal harvested in the west-central portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 501) of all age/sex classes, 1970 – 2003.............................................. 44
Figure 54. Derivation of Blue-winged Teal harvested in the southern portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 458) of all age/sex classes, 1970 – 2003. ............................................ 44
Figure 55. Derivation of Blue-winged Teal harvested in the Gulf Coast region of the Mississippi Flyway
(shaded) based on direct recoveries (n = 2,854) of all age/sex classes, 1970 – 2003 .......................................... 45
Figure 56. Derivation of Blue-winged Teal harvested in the northern portion of the Atlantic Flyway (shaded)
based on direct recoveries (n = 621) of all age/sex classes, 1970 – 2003. ............................................................. 45
Figure 57. Derivation of Blue-winged Teal harvested in the central portion of the Atlantic Flyway (shaded)
based on direct recoveries (n = 294) of all age/sex classes, 1970 – 2003. ............................................................. 46
Figure 58. Derivation of Blue-winged Teal harvested in the southern portion of the Atlantic Flyway (shaded)
based on direct recoveries (n = 592) of all age/sex classes, 1970 – 2003.............................................................. 46
Figure 59. Derivation of Blue-winged Teal harvested in Mexico (shaded) based on direct recoveries (n = 714)
of all age/sex classes, 1970 – 2003.............................................................................................................................. 47
Figure 60. Derivation of Blue-winged Teal harvested in Central America (shaded) based on direct recoveries
(n = 277) of all age/sex classes, 1970 – 2003............................................................................................................. 48
Figure 61. Derivation of Blue-winged Teal harvested in South America (shaded) based on direct recoveries
(n = 398) of all age/sex classes, 1970 – 2003. ........................................................................................................... 48
Figure 62. Derivation of Blue-winged Teal harvested in the Caribbean (shaded) based on direct recoveries
	
(n = 612) of all age/sex classes, 1970 – 2003 ............................................................................................................ 48
NameL oisft Sofe Tctaibolnes xi
List of Tables
Table 1. Distribution of the Blue-winged Teal harvest for all age/sex classes, 1970 – 2003.............................. 20
Table 2. Distribution of the adult male Blue-winged Teal harvest, 1970 – 2003 ................................................. 31
Table 3. Distribution of the adult female Blue-winged Teal harvest, 1970 – 2003 ............................................. 32
Table 4. Distribution of the immature male Blue-winged Teal harvest, 1970 – 2003. ........................................ 33
Table 5. Distribution of the immature female Blue-winged Teal harvest, 1970 – 2003...................................... 34
Table 6. Derivation of the Blue-winged Teal harvest for all age/sex classes, 1970 – 2003. ............................... 36
Table 7. Derivation of the adult male Blue-winged Teal harvest, 1970 – 2003.................................................... 50
Table 8. Derivation of the adult female Blue-winged Teal harvest, 1970 – 2003................................................. 51
Table 9. Derivation of the immature male Blue-winged Teal harvest, 1970 – 2003 .......................................... 52
Table 10. Derivation of the immature female Blue-winged Teal harvest, 1970 – 2003 ...................................... 53
Distribution and Derivation of the Blue-winged Teal Harvest
Acknowledgments
First and foremost we thank U.S. and Canadian
duck banders for their hard work and dedication
to the resource and also individuals who have
diligently reported bands that they have recovered.
We also thank the many individuals from the U.S.
Fish and Wildlife Service (USFWS) – Division
of Migratory Bird Management, and the Central
Flyway Waterfowl Technical Committee for
providing comments and suggestions throughout the
development of this report. Steve Cordts (Minnesota
Department of Natural Resources [DNR]), Ron
Gatti (Wisconsin DNR), Dave Luukkonen (Michigan
DNR), and Guy Zenner (Iowa DNR) provided state
population data. Pam Garrettson (USFWS) provided
ideas and recovery codes for constructing composite
reporting rates. Michel Gendron (Canadian
Wildlife Service) provided Canadian harvest and
parts collection data, and Ken Richkus, Robert
Raftovich, and Khristi Wilkins (USFWS) provided
U.S. harvest and parts collection data. Brian Hosek
(North Dakota Game and Fish Dept.) provided GIS
support. Finally we extend our gratitude to Graham
W. Smith (U.S. Geological Survey) and David L. Otis
(Iowa State University) for providing peer review of
this document. Mention of trade or product names
does not indicate endorsement; the findings and
conclusions in this article are those of the authors and
do not necessarily represent the views of the U.S.
Fish and Wildlife Service.
xii Distribution and Derivation of the Blue-winged Teal Harvest
ENxaemcueti voef SSuemcmtioarny xiii
Executive Summary
We analyzed banding and recovery data for Blue-winged
Teal (BWTE) during 1970 – 2003 to delineate
breeding reference areas (BRAs; groups of BWTE
breeding areas that have similar band recovery
distributions) along with distribution and derivation
of harvest. Distribution of the harvest is defined
as the proportion of birds from a BRA that were
harvested in a given area, whereas derivation of
the harvest is defined as the proportion of birds
harvested in a given area that came from a BRA.
We delineated 12 BRAs based on 23,279 direct
recoveries (banded birds recovered during the
immediate hunting season after being banded)
and indirect recoveries (banded birds recovered
during subsequent hunting seasons) with known
recovery dates. We created harvest areas to pool
and analyze recoveries. Harvest areas were based
on jurisdictional lines important to management
(e.g., waterfowl management flyways [Flyways] or
groups of countries, depending on size) and were
split into minor harvest areas for more in-depth
analyses. Harvest areas that were based on Flyways
included the U.S. portion only. As a simplification,
we used only direct recoveries (n = 15,153) to
determine distribution and derivation of the BWTE
harvest. Consistently, harvest was distributed in a
southeasterly direction away from BRAs, shifting to
a southerly pattern from the far eastern BRAs.
Combined, 73.5% of the BWTE harvest occurred in
the Mississippi Flyway (44.0%) and Latin America
(29.5%). Lesser proportions of the harvest occurred
in the Central Flyway (15.6%), Canada (6.2%), the
Atlantic Flyway (4.3%), and the Pacific Flyway
(0.5%). Overall, highest proportions of the BWTE
harvested were derived from the Eastern Dakotas
BRA (29.8%), Eastern Saskatchewan/Southwest
Manitoba BRA (16.9%), the Upper Midwest BRA
(12.1%), and Western Saskatchewan BRA (11.0%).
A substantial shift in harvest derivation occurred
during the late-1990s coincident with improvements
in wetland conditions and the presence of 1.2 – 1.4
million ha (3 – 4 million ac) of perennial grassland
cover in the Conservation Reserve Program in the
Eastern Dakotas BRA. During the 1994 – 2003
time period, 42.6% of the total BWTE harvest was
derived from the Eastern Dakotas BRA. During the
3 previous time periods (1970 – 1979, 1980 – 1986,
and 1987 – 1993), 17.3 – 26.8% of the total BWTE
harvest was derived from the Eastern Dakotas
BRA. Harvest rates were substantially higher for
BWTE originating in BRAs east of 87°W than for
those in western BRAs. However, harvest rates
decreased over time for both eastern and western
BRAs. Harvest pressure on birds originating from
BRAs in eastern Ontario, Canada, and farther
east (i.e., east of 87°W) appears to be quite high,
but BWTE originating from western BRAs buffer
harvest of BWTE in eastern harvest areas to some
degree. Harvest pressure on birds originating from
BRAs west of 87°W appears to be quite low. Further
analyses should be conducted to determine whether
survival rates have changed relative to harvest rates,
harvest regulations, and prairie habitat conditions.
xiv Distribution and Derivation of the Blue-winged Teal Harvest xiv Distribution and Derivation of the Blue-winged Teal Harvest
Photo by Craig Bihrle
Name of Section 1
Introduction
Blue-winged Teal (Anas discors; BWTE) are the
second most abundant duck (family Anatidae)
species in North America and are widely distributed
(Rowher et al. 2002). Its breeding range stretches
from the southern high-plains of New Mexico
and Texas in the U.S., north to the boreal forest
of Canada and Alaska, and from the Pacific to the
Atlantic coast above approximately 40°N (Fig. 1;
Bennett 1938, Bellrose 1980, Rowher et al. 2002).
The primary breeding range in the north-central
U.S. and prairie Canada generally contains >85%
of all BWTE breeding pairs (U.S. Fish and Wildlife
Service 2009). These areas in the north-central U.S.
and prairie Canada are denoted Waterfowl Breeding
Population and Habitat Survey (May Survey;
Smith 1995; Fig. 2). Blue-winged Teal are often
the most abundant duck species within its primary
breeding range, with numbers of breeding pairs
quickly diminishing and being sparsely distributed
throughout the remainder of the breeding range
(Bellrose 1980).
Blue-winged Teal are an important species in the
composition of the North American duck harvest,
Introduction 1
Figure 1. Breeding and wintering ranges for Blue-winged Teal (Anas discors; adapted from Bellrose 1980,
Rowher et al. 2002).
2 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 2. Strata and transects for the Waterfowl Breeding Population and Habitat Survey (yellow =
traditional survey area, green = eastern survey area; U.S. Fish and Wildlife Service 2009).
usually ranking as the 3rd or 4th most common duck
species harvested in the U.S. (Raftovich et al. 2009).
Total harvest for BWTE is typically estimated to
be >1 million birds annually, ranging from 193,874
in 1988 to 1,559,761 in 2001 (Fig. 3; Raftovich et
al. 2009, Gendron and Collins 2007). Blue-winged
Teal, because of their early migration chronology,
are somewhat unique compared to most other duck
species in that they are hunted during a special
September teal seasons where they are exposed to
additional harvest beyond the regular duck season.
The September teal season became operational in
1969 as a 9-day hunting season for BWTE, Green-winged
Teal (A. crecca), and Cinnamon Teal (A.
cyanoptera) and was continued until 1988 when it
was suspended due to low abundance indices for
BWTE (Fig. 4) and extraordinary drought in prairie
breeding areas. In 1992, the September teal season
was reinstated with the requirement that the BWTE
population index from the May Survey be above 3.3
million birds to open a September teal season (U.S.
Fish and Wildlife Service 1992). In 1998, a request
from the Central Flyway Council was approved
to expand the September teal season to 16 days
whenever the breeding population index from the
May Survey was above 4.7 million birds (U.S. Fish
and Wildlife Service 1998). The expansion also was
provided to the Mississippi Flyway at that same time,
and subsequently to the Atlantic Flyway in 2009.
Harvest opportunity provided by the September
teal season is clearly an important consideration
in BWTE management as it generally accounts
for approximately 1/3 of the total U.S. portion of
the BWTE harvest, ranging from 23.8% to 59.0%
(Raftovich et al. 2009). Despite increased harvest
opportunity provided by September teal seasons,
a higher proportion of the BWTE harvest occurs
in Latin America relative to other North American
waterfowl species (Botero and Rusch 1988).
Numerous BWTE are banded during pre-season
(i.e., prior to opening of hunting seasons) banding
activities that, for the most part, are intended
primarily for Mallards (A. platyrhynchos) and
Northern Pintail (A. acuta). The Central Flyway
preseason duck banding program, initiated in 1996,
greatly expanded banding efforts in the north-central
states of North Dakota, South Dakota, and Montana.
Moreover, during that same time period, changes in
band types and implementation of a toll-free phone
number to report bands improved band-reporting
rates (Royle and Garrettson 2005) and increased the
number of recoveries available for analysis.
Since BWTE are a broadly distributed species (Fig.
1) the distribution and derivation of their harvest
may vary widely. This could result in annual survival
rates that are heterogeneous among portions of
the overall population. We strove to categorize the
population into portions that could be viewed or
analyzed at levels that would result in homogenous
survival rates and have identifiable connections with
breeding, migration, and wintering grounds that are
of interest to managers and policy makers.
Name Ionft rSoedcutcitoionn 33
Figure 4. Blue-winged Teal breeding population indices from the Waterfowl Breeding Population and
Habitat Survey (Smith 1995, U.S. Fish and Wildlife Service 2009), and all breeding areas. The Traditional
area is represented by strata 1 – 18, 20 – 50, and 75 – 77 (U.S. Fish and Wildlife Service 2009). Data for All
Areas includes survey data from state surveys and beginning in 1990, from the Eastern Survey Area (strata
51 – 72; U.S. Fish and Wildlife Service 2009). Prior to 1990, breeding population indices in eastern breeding
areas were based on their proportional contribution to the overall breeding population index in years where
data was available.
Figure 3. Blue-winged Teal harvests, 1970 – 2003 (Kruse et al. 2002, Gendron and Collins 2007, Kruse 2009).
Latin American harvests (H) for each age/sex class are based on:
HLatin American Area, Age/Sex = [(HU.S., Age/Sex + HCanada, Age/Sex) / (1 – ρAge/Sex)] - (HU.S., Age/Sex + HCanada, Age/Sex).
Year
4 Distribution and Derivation of the Blue-winged Teal Harvest
Objectives
(1) Develop breeding reference areas (BRAs)
for BWTE, and
(2) Determine distribution and derivation of the
BWTE harvest.
Photo by Craig Bihrle
Name of Section Methods
Datasets Used
Breeding population data
Population indices (estimates of abundance) have
been collected as part of the May Survey in the
Traditional Survey Area (Fig. 2; strata 1 – 18, 20
– 50, and 75 – 77) since 1955, and were initiated in
portions of the Eastern Survey Area (Fig. 2; strata
51 – 72) in 1990 (U.S. Fish and Wildlife Service 2009).
Some BRAs (primarily in the contiguous U.S.) are
not covered by the May Survey and in those areas,
we used data from state surveys in Iowa, Michigan,
Minnesota, and Wisconsin, and U.S. Fish and Wildlife
Service (USFWS) plot surveys in portions of New
Hampshire, Vermont, New York, Pennsylvania,
Connecticut, Massachusetts, Rhode Island, New
Jersey, Maryland, and Delaware (i.e., northeast U.S.;
Heusmann and Sauer 2000). For BRAs that did not
have abundance data going back to 1970, we used the
proportion of total BWTE estimated in a given BRA
during years where data are available for all areas
to estimate breeding population size in those BRAs
during years with missing data. This methodology
assumes that there were not drastic changes in
breeding population abundances, or the distribution
of the breeding population amongst regions between
1970 and 1990 – 1995 when estimates became
available in the Eastern Survey Area (Fig. 2).
Banding and band recovery data
There were 730,996 normal, wild BWTE banded
during pre-season (July – September) banding
operations from 1970 – 2003. We excluded birds
banded south of 40°N with the exception of birds
banded and recovered from Delaware, Maryland,
and New Jersey, which comprised a major portion
of a BRA’s banding and recovery data. Other
bandings south of 40°N were geographically
isolated or relatively sparse over time and space
and were excluded. Preseason bandings resulted
in 15,153 direct (recovered during the hunting
season immediately following banding) recoveries
and 8,126 indirect (recovered during subsequent
hunting seasons) recoveries coded as shot or found
dead during the hunting season with known recovery
dates. Recoveries in Latin America from February
to April were included, given extended hunting of
migratory birds in those countries. Finally, bandings
and recoveries from local (LOC; young-of-the-year
birds yet to attain flight) and hatch-year (HY; young-of-
the-year birds that have attained flight) age class
birds were combined as immature birds.
Recoveries must first be weighted to account for
differences in banding effort relative to population
sizes within and among areas and changes in
reporting rates over time to determine distribution
and derivation of harvests (Crissey 1955, Geis 1972).
Therefore, we used similar procedures for weighting
recoveries as Munro and Kimball (1982, see below).
Harvest data
Harvest in the U.S. was estimated from 1970 –
2000 using the mail questionnaire survey (Kruse
et al. 2002), and 2001 – 2003 using the Harvest
Information Program (HIP; Kruse 2009). We
estimated proportion of the harvest comprised by
each age/sex class based on numbers of wings in the
parts collection survey (K. Richkus, pers. comm.).
We allocated wings with unknown age or sex based
on overall proportions in each respective Flyway;
wings of unknown age and sex were distributed
proportionally among each age/sex class. Harvest
data in Canada has been collected in a similar
manner as the mail questionnaire survey in the U.S.,
except that hunters are grouped based on their
likelihood of being active and non-resident aliens
are not part of the parts collection survey in Canada
(Gendron and Collins 2007). Estimates of BWTE
harvest in Canada collected from 1970 – 1974 were
derived using slightly different methodology and
were made comparable to data from post-1974 (M.
Gendron, pers. comm.).
Harvests (HLatin American Area) for each of four Latin
American areas (i.e., Caribbean, Central America,
Mexico, and South America) were estimated by age/
sex class using the proportion (ρ) of bands recovered
in each of these areas. Before determining the
proportion of bands recovered in an area, recoveries
were weighted based on reporting rates (see below).
Proportions of recoveries were then multiplied by
BWTE harvest estimates from the U.S. (HU.S.) and
Canada (HCanada) and the harvest was estimated
using:
HLatin American Area, age/sex class = [(HU.S., age/sex class + HCanada,
age/sex class) / (1 – ρage/sex class)] - (HU.S., age/sexc lass + HCanada, age/
sex class).
Objectives & Methods 5
6 Distribution and Derivation of the Blue-winged Teal Harvest
to help meet assumptions of normality, and used only
records with known recovery dates (n = 23,279) for
analyses using the log-transformed recovery date
derivative (LOGRDATE) as a covariate. We also
used untransformed latitude (RLAT) and longitude
(RLONG) of recoveries as covariates.
To create BRAs that represented homogeneous
units of distributions of band recoveries, we ran a
clustering procedure and then grouped clusters
based on their statistical characteristics and
geographic proximity to one another to form BRAs.
We first used a principle components analysis (PROC
PRINCOMP; SAS Institute 2003) of the correlation
matrix of RLAT, RLONG, and LOGRDATE to
determine scores for principle components 1 and
2 (PC1 and PC2) for each recovery. PC1 and PC2
accounted for 86.1% of the variation for recovery
variables. We exported scores for PC1 and PC2 and
ran separate ANOVAs (PROC GLM) to ensure that
they differed by population stratum and calculated
Tukey-adjusted least-square means (LS Means;
[PC1] P<0.001, F44, 23234 = 19.25; [PC2] P<0.001,
F44, 23234 = 808.97). We then plotted LS Means for PC1
on LS Means for PC2 for each population stratum
and visually grouped strata to form BRAs based
on proximity to each other, continuity on the plot,
geographic location, geographic size of combined
strata, and number of recoveries (Figs. 5 and 6).
Development of Harvest Areas
We delineated minor harvest areas based primarily
on harvest management jurisdictions (e.g., Alberta,
Canada), or broader regional groupings of states or
countries (e.g., Caribbean) and numbers of recoveries
within them. Minor harvest areas were then pooled
into larger harvest jurisdictions to summarize harvest
in major harvest areas. Broader waterfowl harvest
management in the U.S. is delivered by administrative
“Flyways” that are based on the migration and settling
patterns of waterfowl. Therefore, the U.S. portions of
the four Flyways (i.e., Atlantic, Central, Mississippi,
and Pacific) were a natural fit for pooling minor harvest
areas into major harvest areas. Although Canadian
provinces are members of Flyways, they generally
have distinctly different harvest regulations from the
U.S. Therefore, we pooled Canadian minor harvest
areas together at the country scale to form the major
harvest area “Canada”. Minor harvest areas south of
the U.S. were pooled to form the major harvest area
“Latin America”.
Calculation of Distribution
and Derivation of the Harvest
Distribution of the harvest is simply the proportion
of the total weighted recoveries from a BRA that
are harvested in a given harvest area. Derivation of
the harvest reflects the proportion of total weighted
recoveries in a harvest area that came from a given
BRA (Munro and Kimball 1982).
Immature ducks are harvested at higher rates
than adult birds due to age-related differences in
vulnerability (Anderson 1975, Cox et al. 1998, Pace
and Afton 1999). Therefore, harvest data must be
adjusted for differential vulnerability to determine
estimates of abundance (Anderson 1975, Munro and
Kimball 1982). These adjustments can be made
using the ratio of recovery or harvest rates of banded
juvenile birds to that of banded adult birds. We
calculated vulnerability ratios for each breeding
reference area within each time period. Different
ratios of band types were used (see below) resulting
in differences in reporting rates across time, space
and age/sex class. Therefore, we used harvest
rates as opposed to recovery rates to calculate
our vulnerability ratios. We then divided harvest
estimates of immature birds for each sex and time
period by their respective vulnerability ratios.
Development of
Breeding Reference Areas
Anderson and Henny (1972) developed BRAs
for Mallards; however, those areas did not align
with May Survey strata (Smith 1995), and may
not necessarily represent homogeneous units for
analysis of BWTE banding data. Therefore, we
developed BRAs for BWTE with the objectives of
(1) obtaining sample sizes large enough for analysis;
(2) maintaining relatively homogeneous distributions
of BWTE recoveries from BRAs; (3) maintaining
relatively homogeneous BWTE survival rates within
BRAs; and (4) develop geographic reference areas
that are meaningful to managers at both the flyway
and North American Waterfowl Management Plan
levels (North American Waterfowl Management
Plan, Plan Committee 2004).
We pooled all age/sex classes for final distributions
and derivations because numbers of recoveries for
some age/sex classes generally were inadequate
for presentation of results. However, we also have
provided a coarse summary and tables of distribution
and derivation of harvest by age/sex class. As a
conservative measure, we used both direct and indirect
recoveries to develop BRAs, but only direct recoveries
to determine distribution and derivation of the harvest.
We used ArcGIS to identify and assign banding
sites of recoveries to the breeding population strata
within which they were located (Environmental
Systems Research Institute 2009). We excluded any
breeding population strata with fewer than 20 total
recoveries that originated within their boundaries
for analyses to develop BRAs, but later included
them within appropriate BRAs for distribution
and derivation analyses. We used the following
Julian-date derivative to represent recovery dates
in analyses. Because recoveries beginning on New
Year’s Day are actually at the end of the annual
hunting season, we added 365 to the Julian dates of
recoveries from January through early April. We then
log-transformed Julian-date derivatives for recoveries
Name of SeMcettihoond s 7 7
Figure 6. Least squares means of principal component 1 vs. least squares means of principal component 2
derived from recovery latitude, longitude, and log-transformed recovery date of Blue-winged Teal (n =
23,279) by their breeding population strata of the Waterfowl Breeding Population and Habitat Survey (U.S.
Fish and Wildlife Service 2009), after grouping into breeding reference areas (BRAs; 1 = Central Alberta,
2 = Southern Alberta, 3 = Western Saskatchewan, 4 = Eastern Saskatchewan/Southwest Manitoba, 5 =
Westcentral Manitoba, 6 = Northern Great Plains, 7 = Eastern Dakotas, 8 = Upper Midwest, 9 = U.S.
Great Lakes, 10 = Eastern Ontario/Southern Quebec, 11 = Maritimes/Maine, and 12 = Northeast States).
Figure 5. Least squares means of principal component 1 vs. least squares means of principal component
2 derived from recovery latitude, longitude, and log-transformed recovery date of Blue-winged Teal (n
= 23,279) by their breeding population strata of the Waterfowl Breeding Population and Habitat Survey
(U.S. Fish and Wildlife Service 2009). States or regions treated as strata were given unique numbers
(200 = Minnesota, 201 = Iowa, 202 = Wisconsin, 203 = Michigan, 204 = Ohio, 207 = Pennsylvania, 208
= Maryland, 209 = Delaware, 300 = New York, 301 = Vermont, 304 = Massachusetts, and 307 = Gaspe
Peninsula region of Quebec).
8 Distribution and Derivation of the Blue-winged Teal Harvest
Recovery weights
Breeding population sizes and banding efforts have
varied among years within and among BRAs. To
more accurately reflect the representativeness of each
recovered band, recoveries must be weighted to account
for spatial and temporal differences in bird abundance
and banding effort. We used methodology similar to
that described by Munro and Kimball (1982) to weight
recoveries for analysis. Using this methodology
requires four main types of data: (1) breeding
population estimates; (2) harvest estimates; (3) banding
and band recovery data; and (4) band-reporting rates.
Pooling data among years
Most BRAs had low numbers of recoveries in some
years due to sporadic banding efforts across time, and
greatly reduced harvest effort (i.e., no September teal
seasons) during some years. Therefore, we pooled
data within each of four time periods (i.e., 1970 – 1979,
1980 – 1986, 1987 – 1993, and 1994 – 2003) based on
wetland conditions in the primary breeding range
of BWTE. Wetland count data by the USFWS for
the north-central U.S. (i.e., strata 41 – 49 of the May
Survey; Fig. 2) began to be corrected for visibility bias
in 1974; however, the North Dakota Game and Fish
Department (NDGFD) began wetland count estimates
in North Dakota in 1948 and for 1970 – 1973, we used
a simple regression (Fig. 7; R2 = 0.72) using wetland
survey data from NDGFD (1974 – 2008) to predict
USFWS count estimates for the north-central U.S.
during those years. We then estimated mean numbers
of wetlands in north-central U.S. and Prairie Canada
(Strata 26 – 40; Figs. 2 and 8).
Band-reporting rates
Band-reporting rate studies have not been conducted
for BWTE. Therefore, we used reporting rates as
described for Mallards (Henny and Burnham 1976,
Nichols et al. 1991, C. Moore, pers. comm.) and Wood
Ducks (Aix sponsa; P. R. Garrettson, pers. comm.).
Moreover, band-reporting rates from Latin America
are unknown. Differing languages, lack of English
literacy or exposure to the English language, and lack
of telephones or computers available by individuals
recovering bands in many areas of Latin America is a
barrier to reporting of recovered bands (Botero 1992).
Therefore, we assumed that recoveries in Latin
American countries were being reported at one-half
the rate of recoveries in the U.S. This assumption is
a compromise between not including Latin American
recoveries, which are numerous, and assuming that
Latin American band-reporting rates are equal to
those in the U.S. For example, if a reporting rate in
the U.S. for a given band type × reporting method
was 32% the reporting rate for a recovery of the same
Figure 7. May pond counts in North Dakota, 1974 – 2008, from the North Dakota Game and Fish Breeding
Duck Survey (M. A. Johnson, pers. comm.) and the Waterfowl Breeding Population and Habitat Survey
(Strata 41 – 49; Smith 1995, U.S. Fish and Wildlife Service 2009) used to estimate numbers of ponds in the
north-central U.S. prior to 1974.
Name of SMecettihoond s 99
band type × reporting method in a Latin American
country would be 16%. Reporting rates for solicited
recoveries remained 100%, regardless of area.
Although our assumptions for reporting rates in Latin
America could be challenged, professionals who have
worked in these areas believe that band-reporting
rates in Latin America are quite low (Botero 1992).
Accurate estimates of band-reporting rates are
required to calculate harvest rates. Over the 34-
year period, band types and reporting methods
have changed numerous times, resulting in different
reporting rates (Henny and Burnham 1976, Nichols
et al. 1995). Reporting rates for Mallards also varied
spatially and temporally (e.g., Nichols et al. 1995).
Since we pooled data across time with different band
types used and banding efforts within and among
BRAs, we had additional need to reconcile reporting
rates (Fig. 9). We used a composite reporting rate
(P. R. Garrettson, pers. comm.) to calculate reporting
rates for each time period, BRA, and age/sex class.
The composite reporting rate is essentially a weighted
average, in which the summed actual recoveries are
divided by the summed expected recoveries for a sub-set
of recoveries in question. The number of expected
recoveries for each band type/reporting method
combination would be the number of recoveries
multiplied by the inverse of that band type/reporting
method’s band-reporting rate.
Estimation of the age and sex structure
of the preseason population
Because age/sex classes are rarely banded in
proportion to their abundance, we needed to estimate
their relative preseason abundance just prior
to the hunting season to account for differences in
banding effort. Breeding population indices are
comprised of unknown compositions of adult males and
females. Moreover, estimates of production are needed
to represent young birds in the fall flight. For these
estimations, we combined LOC birds with HY birds.
We used Lincoln’s (1930) method to obtain independent
estimates of each of the four age/sex class’s abundance
(N) prior to the hunting season for time period (t)
using harvest estimates (H) and harvest rates (h):
Nt, age/sex class = Ht, age/sex class / ht, age/sex class.
Thus, the direct recovery rate (f ) is determined by
the sum of direct recoveries (d) for each age/sex
class within each BRA (i), during a time period (t),
over years (y), divided by total bandings (b) for each
age/sex class. Harvest rate for a time period is the
product of the proportional contribution of a BRA’s
breeding population (Bpopi ) to the overall population
size (Bpop) during a time period and the BRA’s direct
recovery rate for a time period (f i,t) divided by the
BRA’s composite reporting rate during the time
period (λComp i, t) and then summed over the 12 BRAs.
All parameters were calculated separately for each of
the four age/sex classes.
Figure 8. Average numbers (± 95% CL) of May ponds in Prairie Canada (Strata 25 – 40) and North-central
U.S. (strata 41 – 49) from the Waterfowl Breeding Population and Habitat Survey (Smith 1995, U.S. Fish
and Wildlife Service 2009) by time period.
10 Distribution and Derivation of the Blue-winged Teal Harvest
For each sex:
t, i , Juv = [(Nt, i , IM + Nt, i , IF / (Nt, i , AM + Nt, i , AF )) * Bpopi,t] * 0.5
Assumptions (Munroe and Kimball 1982) that pertain
to the above calculations are: (1) the populations
(in our case, birds within BRAs) remain unchanged
during the preseason banding period; (2) the banded
samples are representative of the populations with
respect to mortality, movement and migration; (3) the
harvest area is large enough to include an adequate
sample from all banded populations; (4) recruitment
is uniform among all populations; (5) the adult sex
ratio is uniform among all populations; and (6) band-reporting
rates are accurately estimated.
Spatial Analysis of Recoveries
We conducted simple density analyses of direct
recoveries using Spatial Analyst in ArcGIS
(Environmental Systems Research Institute 2009).
We used the weighted recoveries (as calculated
above) as the population field, a search radius of 41
km, and output cell size of 5 km x 5 km. We then
classified cell values into relative percentiles (lower
percentile equals a lower density), specific to each
map. That is, a harvest density percentile for each
BRA, larger area, or bi-weekly period, depending on
breakdown of data was used for each map.
Band-recovery weights are the quotient of the
preseason population estimate of each age/sex class
divided by the number of each age/sex class banded
specific to each time period and BRA and multiplied by
the inverse of the appropriate composite reporting rate.
For example, the calculation for adult males was:
and,
where i = 1, 2…12 breeding reference areas.
Thus, to determine preseason estimates of adult male
and female abundance:
t, i , AM = (Nt, i , AM / (Nt, i , AM + Nt, i , AF )) * Bpopi,t
t t, i , AF = (Nt, i , AF / (Nt, i , AM + Nt, i , AF )) * Bpopi,t
The immature preseason population estimate is
presumed to be split equally between sexes and is the
age ratio of the indirect population estimates for time
period (t) multiplied by Bpopi,t .
Figure 9. Composite band-reporting rates for Blue-winged Teal by breeding reference area and time
period. Composite band-reporting rates are the weighted average of reporting rates for different reporting
methods used to report recoveries.
Name of SMecettihoond s 11
Results and Discussion
Breeding Reference Areas
and Harvest Areas
The analysis of data from population survey strata
suggested 12 BRAs (Fig. 10). Numbers of direct
recoveries from each BRA (1970 – 2003) ranged from
592 in the Northeast States BRA to 3,168 from the
Eastern Saskatchewan/Southwest Manitoba BRA
(Appendix A). The mean of the total number of
direct recoveries from all BRAs equaled 1,258.25 (SE
= 206.28).
We delineated six major harvest areas (Canada, Pacific
Flyway, Central Flyway, Mississippi Flyway, Atlantic
Flyway, and Latin America) for summarization of
recovery data. Additionally, we used 22 minor harvest
areas to summarize harvest at a finer scale (Fig. 11).
Minor harvest areas had considerable range in area
based on harvest density, but were also designed to
align with boundaries used in harvest management.
For example, the Mississippi Flyway – Gulf Coast
minor harvest area had high numbers of recoveries,
but is only 64,676 km2, whereas the Quebec minor
harvest area had somewhat low numbers of recoveries
and is 2,652,642 km2.
Recovery Weight Components
Composite reporting rates
For purposes of illustration and simplicity, we
describe overall composite reporting rates, whereas
Figure 10. Map showing breeding reference areas for Blue-winged Teal. Breeding reference areas are
geographically aggregated portions of the population that have similar band recovery distributions).
12 Distribution and Derivation of the Blue-winged Teal Harvest
regional rates likely have changed with the advent of
more user-friendly reporting methods (i.e., toll-free
telephone numbers, and websites). More recently,
Otis et al. (2008) described fairly drastic differences
in regional reporting rates in the U.S. for Mourning
Doves (Zenaida macroura). However, we did not feel
that it was appropriate to apply these differences to a
waterfowl species and expect that regional differences
in reporting rates for BWTE are similar to those for
Mallards, but must acknowledge that large regional
differences in reporting rates for BWTE could exist.
Well-defined estimates of reporting rates from Latin
America do not exist, so we made the assumption
that those reporting rates were 50% of the defined
U.S. reporting rate. Band-reporting rates, excluding
solicited bands which always have a reporting rate
of 1, under this assumption would range from 0.16
for mail address (i.e., AVISE bands, which had only
“Write Washington DC” etched on them) bands
reported by mail to 0.37 for toll-free telephone
number bands that were reported via telephone.
We felt that making this “crude” assumption was
necessary to include bands that were recovered in
in calculations for determining harvest rates, we used
composite rates specific to age/sex classes.
Overall, composite reporting rates varied across BRAs
and time period (Fig. 9). The range of composite
reporting rates was similar during the first three time
periods (1970 – 1979, 1980 – 1986, and 1987 – 1993),
ranging from 0.24 (Northern Great Plains BRA, 1979 –
1979) to 0.41 (Eastern Ontario/Southern Quebec BRA,
1987 – 1993). Within these time periods, composite
reporting rates for some BRAs did not vary (e.g.,
Eastern Saskatchewan/Southwestern Manitoba BRA,
0.30 [1970 – 1979], 0.30 [1980 – 1986], 0.29 [1987 – 1993]),
while composite reporting rates fluctuated among time
periods for other BRAs (e.g., Eastern Dakotas BRA,
0.30 [1970 – 1979], 0.39 [1980 – 1986], 0.33 [1987 – 1993]).
During 1994 – 2004, composite reporting rates increased
substantially, ranging from 0.48 (U.S. Great Lakes
BRA) to 0.76 (Upper Midwest BRA), coincident with
deployment of toll-free bands on Mallards.
We did not apply slight regional differences (e.g., 0.29
versus 0.34) in reporting rates in the U.S. or Canada,
as described for Mallards (Nichols et al. 1995). These
Figure 11. Map showing minor harvest areas for Blue-winged Teal. Minor harvest areas are based on
harvest jurisdictions such as states, or portions of Flyways (PF = Pacific Flyway, CF = Central Flyway,
MF = Mississippi Flyway, AF = Atlantic Flyway). Flyways are aggregations of states, parts of states, and
provinces and are the delivery mechanism for harvest management. Only U.S. portions of Flyways are used
and Canadian portions are described separately.
Name of SMecettihoond s 13
Latin American countries as they accounted for 13.2%
of all direct recoveries, and even higher proportions
for some BRAs. Our estimate that reporting rates
were 50% of those defined in the U.S. may still be
higher than actual reporting rates in Latin America
and underestimate harvests of BWTE in Latin
America, and importance of harvest in those areas to
some BRAs. Based on bands recovered by hunters in
a small village, Botero (1992) surmised that reporting
rates in Latin America are substantially lower than
U.S. reporting rates. Remote areas in Latin America
that lack telephones or internet likely have very low
reporting rates (Botero and Rusch 1988, Botero 1992),
whereas areas in Mexico or the Caribbean where
wealthy, often English-literate hunters are guided,
likely have higher band-reporting.
Harvest rates
Harvest rates varied substantially among BRAs,
time periods, and cohorts (Appendix B). Overall,
harvest rates were similar between immature male
and female BWTE from the same BRA and time
period. As expected, immature BWTE almost always
had higher harvest rates than adults. Harvest
rates for adult female BWTE were often similar to,
but occasionally higher than those of males from
the same BRA and time period. Although males
comprise a majority of the September teal season
harvest, females periodically exceed males in the
regular season harvest. Early departure of many
male BWTE may result in greater harvest exposure
on remaining female BWTE during regular duck
seasons, which occur from late-September through
January in the U.S. Regular duck hunting seasons
have about four times as many days available for
hunting and bag limits that are generally higher than
those during September teal seasons.
Harvest rates were higher for birds originating from
BRAs east of 87°W than those originating from BRAs
west of that line, compared within time periods, but
regardless of age/sex class. Harvest rates were
highest during the 1970 – 1979 time period, followed
by the 1980 – 1986 time period. Harvest rates were
similar between the 1987 – 1993 and 1994 – 2003
time periods, and were approximately half of those
observed during the 1970 – 1979 time period. These
reductions in harvest rates for birds in eastern
harvest areas were likely the result of significant
restrictions in BWTE harvest frameworks in Quebec,
beginning in 1991, that reduced the daily bag limit
of BWTE to 1 or 2 BWTE/day from a daily bag limit
that was formerly equal to the overall duck bag
limit (generally 6 – 8 ducks/day). Annual harvest
of BWTE in Quebec averaged 35,326 during 1970 –
1979, 11,306 during 1980 – 1986, 5,327 during 1987 –
1993, and 4,192 during 1994 – 2003.
Birds originating from some eastern BRAs
experienced much higher harvest rates during
the 1970 – 1979 time period (e.g., immature males
from Eastern Ontario/Southern Quebec BRA, 0.35;
Appendix B) as compared to much lower harvest
rates for birds from western BRAs during the same
time period (e.g., immature males from the Central
Alberta BRA, 0.05; Appendix B). Nonetheless, birds
from some western BRAs also experienced relatively
high harvest rates during the 1970s (e.g., immature
females from the West-central Manitoba BRA, 0.14;
Appendix B). Harvest rates declined substantially
for most areas over the next two time periods, often
hitting low-points during the 1987 – 1993 time period
when no September teal seasons were held. Harvest
rates experienced during the 1994 – 2003 time period
were nearly identical to the 1987 – 1993 time period
despite resuming September teal seasons. These
two most recent time periods had exceptionally low
harvest rates (often less than 0.03 in western BRAs;
Appendix B), with the exception of eastern BRAs.
Birds from eastern BRAs were still harvested at
rates nearly twice as high as birds from western
BRAs (Appendix B).
We did not calculate estimates of reporting rates
that varied geographically (other than that already
described for Latin America) as have some
researchers for other species (Henny and Burnham
1976, Nichols et al. 1995, Otis et al. 2008). We
believe that these effects would be more likely for
birds originating in western BRAs; however, the
cumulative effects on harvest rates likely would
be negligible given low harvest rates for birds
originating west of 87°W. Moreover, given that
reporting rates in Latin America may be quite low
(Botero 1992), reporting rates that we used for
recoveries in Latin America (0.16 – 0.37) may be
liberally high and underestimate the importance of
Latin American areas to the harvest of BWTE.
Preseason population structure
Because we pooled data into time periods, we present
preseason population structures for the four time
periods: 1970 – 1979, 1980 – 1986, 1987 – 1993, and
1994 – 2003. Our population estimates prior to the
hunting season for adults were 1.62, 2.81, 1.86, and 2.59
times larger, respectively, than population estimates
obtained from the May Survey. Our indirect population
estimates could be higher than those from the May
survey for several reasons: (1) the May population
estimates are biased low and our estimates are correct;
(2) harvest estimates may be biased high which would
inflate our indirect population estimates (Padding and
Royle 2012); (3) reporting rates may be underestimated,
resulting in harvest rates that are biased low and inflate
our indirect population estimates; (4) BWTE outside
of areas represented by banding information, and
inclusion in harvest rate calculations, have an extremely
large contribution to harvest estimates; and (5) some
unknown combination of the preceding scenarios.
Based on harvest survey data from the U.S. and
Canada, sex ratios (male/female) used to determine
adult male and female composition of the population
prior to the hunting season were: 1.2, 1.72, 2.22, and
1.64, respectively for the four time periods listed
above. Based on harvest survey data from the U.S. and
Canada, age ratios (immature/adult) used to determine
14 Distribution and Derivation of the Blue-winged Teal Harvest
the size of the immature population prior to hunting
seasons were: 1.01, 0.82, 1.08, and 1.13, respectively for
the four time periods listed above.
Band recovery weights
Recovery weights varied substantially among BRAs
and time periods (Appendix C). Some BRAs such as
the Northern Great Plains BRA, Eastern Dakotas
BRA, and Upper Midwest BRA were, at times, grossly
under-represented in bandings relative to population
size. Conversely, BWTE in other BRAs were banded
disproportionately greater than population size. For
example, BWTE in BRAs east of 87°W represented
25.4% of direct recoveries before weighting, and only
5.6% after weighting. Generally, weightings were
most consistent for bands from the Southern Alberta
and Western Saskatchewan BRAs where banding
efforts have been relatively constant over time.
Distribution and Relative Density
of the Blue-winged Teal Harvest
from Breeding Reference Areas
to Major and Minor Harvest Areas,
1970 – 2003.
Blue-winged Teal begin their southward migration in
the fall as early as late August. Birds typically follow
the flyway most near their nesting area, although
some crossing over from one flyway to another
occurs. The majority of the birds use the Mississippi
and Central flyways; relatively small numbers
migrate down the Pacific and Atlantic flyways. The
flights within flyways are not straight north and
south, but rather follow natural waterways (Bennett
1938). The birds spend about 6-8 weeks in migration
before reaching their wintering areas.
The migration patterns influence the geographic
distribution of the harvest, with birds using the
Mississippi and Central flyways comprising the
majority of the annual harvest. Although less is
known about the ecology and harvest of birds south
of the U.S. border, significant concentrations occur
in many areas of Mexico, Central America, and
South America. Following are descriptions of the
distribution and derivation of harvests.
All age/sex classes
The Mississippi Flyway (44%), Latin America
(29.5%), and the Central Flyway (15.6%) were the
most important major harvest areas for BWTE.
Mississippi Flyway – Gulf Coast (19.2%), Mississippi
Flyway – Northwest (17.4%), Mexico (13%), and
Central Flyway Low Plains – South (11.5%) were the
most important minor harvest areas for BWTE (Table
1). Overall, the greatest harvest densities for BWTE
occurred along the Gulf Coast region of Louisiana and
Texas, followed by north-central Iowa, east-central
Wisconsin, and west-central Minnesota (Fig. 12).
Breeding reference areas west of 87°W
The Mississippi Flyway (46%), Latin America (29.9%),
and the Central Flyway (16.5%) were the most
important major harvest areas for BWTE originating
west of 87°W. Mississippi Flyway – Gulf Coast
(20.2%), Mississippi Flyway – Northwest (18.4%),
Mexico (13.8%), and Central Flyway Low Plains –
South (12.2%) were the most important minor harvest
areas for BWTE originating west of 87°W (Fig. 13).
Central Alberta BRA.—Latin America (45.7%) was the
most important major harvest area for BWTE from
the Central Alberta BRA. Mexico (25.3%), Mississippi
Flyway – Gulf Coast (18.0%), Central America (11.2%),
and Central Flyway Low Plains – South (11.3%) were
important minor harvest areas for birds originating
from this area. Few BWTE from this area were
harvested in Caribbean countries (2.6%; Table 1; Fig.
14). The highest harvest densities of BWTE from this
area occurred in the Gulf Coast region of Louisiana
and Texas, and areas of Mexico (Fig. 15).
Southern Alberta BRA.—Of the major harvest
areas, Latin America harvested the highest
proportion (52.5%) of BWTE from this area. Unlike
BWTE from the Central Alberta BRA, many birds
originating from this area (11.2%) were harvested
in Alberta. Mexico (36.1%) and Mississippi Flyway
– Gulf Coast (13.2%) were important minor harvest
areas. Similar to harvest distribution from the
Central Alberta BRA, Central America (10.9%) was
also an important minor harvest area, and few (1.4%)
birds were harvested in Caribbean countries (Table
1, Fig. 16). The highest harvest densities of BWTE
from this area occurred in southern Alberta, the Gulf
Coast region of Louisiana and Texas, and areas of
Mexico (Fig. 17).
Western Saskatchewan BRA.—Latin America
(38.5%) and the Mississippi Flyway (37.7%) were
equally important major harvest areas for BWTE
from the Western Saskatchewan BRA. Mississippi
Flyway – Gulf Coast (20.4%), Mexico (19.5%), Central
Flyway Low Plains – South (13.3%), and Mississippi
Flyway – Northwest (10.0%) were important minor
harvest areas for these birds (Table 1, Fig. 18). The
highest harvest densities of BWTE from this region
occurred in the Gulf Coast region of Louisiana and
Texas, and the Central Highlands of Mexico (Fig. 19).
Eastern Saskatchewan/Southwest Manitoba
BRA.—The Mississippi Flyway (44.3%) was the
most important major harvest area for BWTE from
this area. Mississippi Flyway – Gulf Coast (21.7%),
Mississippi Flyway – Northwest (14.2%), Mexico
(11.7%), and Central Flyway Low Plains – South
(10.6%) were the most important minor harvest
areas for birds originating in this area (Table 1, Fig.
20). Southwest Manitoba and the Gulf Coast region
of Louisiana and Texas are areas of highest harvest
density of BWTE from this region, with moderate
harvest densities in many other areas (Fig. 21).
ReNsualtms ean odf DSiesccutsiosino n 1155
Figure 12. Relative harvest density derived from direct recoveries (n = 15,099) of Blue-winged Teal from all
breeding reference areas and all sex/age classes, 1970 – 2003.
Figure 13. Relative harvest density derived from direct recoveries (n = 11,254) of Blue-winged Teal banded
in breeding reference areas west of 87°W for all age/sex classes, 1970 – 2003.
16 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 14. Distribution of the Blue-winged Teal harvest based on direct recoveries (n = 756), from the
Central Alberta Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 15. Relative harvest density derived from direct recoveries (n = 756) of Blue-winged Teal banded in
the Central Alberta Breeding Reference Area for all age/sex classes, 1970 – 2003.
ReNsualmts ea nodf DSiesccutisosino n 1177
Figure 16. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 819), from the
Southern Alberta Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 17. Relative harvest density derived from direct recoveries (n = 819) of Blue-winged Teal banded in
the Southern Alberta Breeding Reference Area for all age/sex classes, 1970 – 2003.
18 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 18. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,140), from the
Western Saskatchewan Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 19. Relative harvest density derived from direct recoveries (n = 1,140) of Blue-winged Teal banded in
the Western Saskatchewan Breeding Reference Area for all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 19
Figure 20. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 3,168), from the
Eastern Saskatchewan/Southwest Manitoba Breeding Reference Area (shaded) for all age/sex classes,
1970 – 2003.
Figure 21. Relative harvest density derived from direct recoveries (n = 3,168) of Blue-winged Teal banded in
the Eastern Saskatchewan/Southwest Manitoba Breeding Reference Area for all age/sex classes, 1970 – 2003.
20 Distribution and Derivation of the Blue-winged Teal Harvest
Table 1. Distribution of the Blue-winged Teal harvest for all age/sex classes, 1970 - 2003.
West-central Manitoba BRA.—Similar to BWTE from
the eastern Saskatchewan/Southwest Manitoba BRA,
53.7% of the BWTE from this area were harvested
in the Mississippi Flyway major harvest area.
Mississippi Flyway – Northwest (31.0%), Mississippi
Flyway – Gulf Coast (14.6%), and Caribbean countries
(8.4%) were the most important minor harvest areas
for these birds (Table 1, Fig. 22). The highest harvest
densities of BWTE from west-central Manitoba
occurred in south-central Manitoba, south-central
Minnesota, east-central Wisconsin, the Gulf Coast
region of Louisiana, and Haiti (Fig. 23). Blue-winged
Teal from this BRA appear to have considerably more
exposure to harvest than birds from most other BRAs
west of 87°W (Table 1, Fig. 23).
Northern Great Plains BRA.—Similar to birds
from Alberta, 50.9% of BWTE from this area were
harvested in the Latin America major harvest area;
however, Caribbean countries only accounted for
2.1% of the total harvest of BWTE from the Northern
Great Plains BRA. Central Flyway Low Plains –
South (15.6%) and Mississippi Flyway – Gulf Coast
(10.9%) were the most important minor harvest areas
for these birds (Table 1, Fig. 24). The highest harvest
densities of BWTE from this region occurred in the
Gulf Coast region of western Louisiana into Texas,
and throughout Mexico (Fig. 25).
ReNsualtms aen do fD Siseccutsisoionn 21
Figure 22. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,802), from the
West-central Manitoba Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 23. Relative harvest density derived from direct recoveries (n = 1,802) of Blue-winged Teal banded in
the West-central Manitoba Breeding Reference Area for all age/sex classes, 1970 – 2003.
22 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 24. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 815), from the
Northern Great Plains Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 25. Relative harvest density derived from direct recoveries (n = 815) of Blue-winged Teal banded in
the Northern Great Plains Breeding Reference Area for all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 23
Eastern Dakotas BRA.—The Mississippi Flyway
(49.1%) was the most important major harvest area
for BWTE from this area. However, the Central
Flyway and Latin America major harvest areas also
accounted for 23.5% and 22.7%, respectively, of the
total harvest of BWTE originating in the Eastern
Dakotas BRA. Mississippi Flyway – Gulf Coast
(26.6%), Central Flyway Low Plains – South (17.1%),
and Mississippi Flyway – Northwest (14.5%) were the
most important minor harvest areas for these birds
(Table 1, Fig. 26). Blue-winged Teal from this BRA
are harvested at their highest densities in the Gulf
Coast region of Louisiana and Texas, and east-central
Wisconsin, with many other areas experiencing
relatively low harvest densities (Fig. 27).
Upper Midwest BRA.—The Mississippi Flyway
(76.0%) was by far the most important major
harvest area for BWTE from this area. Mississippi
Flyway – Northwest (54.6%) and Mississippi Flyway
– Gulf Coast (13.1%) were the most important
minor harvest areas for these birds. This BRA
is unique in that most of the birds harvested in
this area originated within the BRA (Table 1, Fig.
28). Given that most BWTE recoveries from this
BRA also occurred in the same harvest area, it is
not surprising that the highest harvest density for
these birds occurred in north-central Iowa, with
relatively moderate harvest densities also occurring
throughout Minnesota, east-central Wisconsin, and
the Gulf Coast region of Louisiana (Fig. 29). Blue-winged
Teal from this BRA, along with those from
west-central Manitoba, appear to have considerably
more exposure to harvest than birds from other
BRAs west of 87°W (Table 1).
Breeding reference areas east of 87°W
Canada (48.2%), the Atlantic Flyway (22.9%), and Latin
America (18.9%) were the most important minor harvest
areas for BWTE originating east of 87°W. Ontario
(36.2%), Caribbean countries (15.5%), and Quebec (9.2%)
were the most important harvest areas for BWTE
originating east of 87°W (Table 1, Fig. 30). The highest
harvest densities of BWTE east of 87°W were along
the St. Lawrence River, and eastern Great Lakes. The
Gulf Coast region of eastern Louisiana and much of the
eastern Caribbean also had relatively moderate harvest
densities of BWTE from east of 87°W (Fig. 30).
U.S. Great Lakes BRA.—This area is the westernmost
BRA east of 87°W, which represents a major division in
the distribution of harvest of BWTE. Canada (44.3%)
was the most important major harvest areas for BWTE
from this BRA. However, 27.1% of the total harvest of
this area’s birds occurred in Latin America. Ontario
(41%), Caribbean countries (16.6%), Mississippi Flyway
– Northeast (10.6%), and South America (9.8%) were
the most important minor harvest areas for these birds
(Table 1, Fig. 31). High harvest density areas for these
birds occurred mostly along the St. Lawrence River and
eastern Great Lakes, with areas of moderate harvest
density in the Gulf Coast region of eastern Louisiana
and Haiti. Much of Michigan, southern Florida, and the
Caribbean had areas with relatively low harvest densities
of BWTE from the U.S. Great Lakes BRA (Fig. 32).
Eastern Ontario/Southern Quebec BRA.—Similar to the
U.S. Great Lakes BRA, Canada (64.4%) was the most
important major harvest area for birds originating in
the Eastern Ontario/Southern Quebec BRA. Ontario
(44.6%), Quebec (19.8%), Atlantic Flyway – North
(11.4%), and Caribbean countries (10.2%) were the most
important minor harvest areas for these birds (Table
1, Fig. 33). Similar to birds from the U.S. Great Lakes
BRA, high harvest density areas for BWTE from this
region occurred mostly along the St. Lawrence River and
eastern Great Lakes, with areas of low harvest density in
the Gulf Coast region of eastern Louisiana and across the
Caribbean (Fig. 34).
Maritimes/Maine BRA.—Similar to the two
aforementioned BRAs, Canada (45.2%) was the most
important major harvest area for birds originating in
the Maritimes/Maine BRA. Latin America (33.7%) was
also an important major harvest area for birds from
this BRA; however, virtually no BWTE from this area
were harvested in Mexico or Central America. The
Maritimes provinces (32.9%), Caribbean countries
(22.3%), Atlantic Flyway – North (15.1%), Quebec
(12.1%), and South America (11.2%) were the most
important minor harvest areas for these birds
(Table 1, Fig. 35). Highest harvest density areas of
BWTE from this region occurred along the Atlantic
coast of the southern Maritimes and southern Maine,
and in the eastern Lesser Antilles Islands. Areas of
relatively moderate harvest density of BWTE from the
Maritimes and Maine occurred near the St. Lawrence
River, the Gulf Coast region of eastern Louisiana, and
across the eastern Caribbean (Fig. 36).
Northeast States BRA.—The Atlantic Flyway (56.1%)
was the most important major harvest area for BWTE
from this area. However, Latin America (35.0%) also
accounted for a large portion of the harvest of these
birds. Caribbean countries (26.3%), Atlantic Flyway –
Central (25.6%), and Atlantic Flyway – North (22.1%)
were the most important minor harvest areas for these
birds (Table 1, Fig. 37). Highest harvest density areas
for BWTE from the Northeast States BRA occurred
near Long Point, Ontario, Chesapeake Bay, and Haiti.
Relatively moderate harvest density for these birds
occurred in the Finger Lakes Region of New York, and
across the eastern Caribbean, particularly the Lesser
Antilles Islands (Fig. 38).
All breeding reference areas by age/sex class
Adult males. —The Mississippi Flyway (46.5%), Latin
America (34.7%), and the Central Flyway (11.6%) were
the most important major harvest areas for adult male
BWTE. Mississippi Flyway – Gulf Coast (25.9%), Mexico
(16.5%), Mississippi Flyway – Northwest (15%), and
Central Flyway Low Plains – South (10%) were the most
important minor harvest areas for adult male BWTE
(Table 2).
24 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 26. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,852), from the
Eastern Dakotas Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 27. Relative harvest density derived from direct recoveries (n = 1,852) of Blue-winged Teal banded in
the Eastern Dakotas Breeding Reference Area for all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 25
Figure 28. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 902), from the
Upper Midwest Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 29. Relative harvest density derived from direct recoveries (n = 902) of Blue-winged Teal banded in
the Upper Midwest Breeding Reference Area for all age/sex classes, 1970 – 2003.
26 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 30. Relative harvest density derived from direct recoveries (n = 3,845) of Blue-winged Teal banded in
breeding reference areas east of 87°W for all age/sex classes, 1970 – 2003.
Figure 31. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,033), from the
U.S. Great Lakes Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 27
Figure 32. Relative harvest density derived from direct recoveries (n = 1,033) of Blue-winged Teal banded in
the U.S. Great Lakes Breeding Reference Area for all age/sex classes, 1970 – 2003.
Figure 33. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,093), from the
Eastern Ontario/Southern Quebec Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
28 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 35. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 1,127), from the
Maritimes/Maine Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 34. Relative harvest density derived from direct recoveries (n = 1,093) of Blue-winged Teal banded in
the Eastern Ontario/Southern Quebec Breeding Reference Area for all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 29
Figure 37. Distribution of the Blue-winged Teal harvest, based on direct recoveries (n = 592), from the
Northeast States Breeding Reference Area (shaded) for all age/sex classes, 1970 – 2003.
Figure 36. Relative harvest density derived from direct recoveries (n = 1,127) of Blue-winged Teal banded in
the Maritimes/Maine Breeding Reference Area for all age/sex classes, 1970 – 2003.
30 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 38. Relative harvest density derived from direct recoveries (n = 592) of Blue-winged Teal banded in
the Northeast States Breeding Reference Area for all age/sex classes, 1970 – 2003.
Adult females.—The Mississippi Flyway (43.5%), Central
Flyway (22.5%), and Latin America (24.2%) were the
most important major harvest areas for adult female
BWTE. Central Flyway Low Plains – South (19.9%),
Mississippi Flyway – Gulf Coast (18.4%), and Mississippi
Flyway – Northwest (17.3%) were the most important
minor harvest areas for adult female BWTE (Table 3).
Immature males.—The Mississippi Flyway (41.3%),
Latin America (29.8%), and the Central Flyway (17.3%)
were the most important major harvest areas for
immature male BWTE. Mississippi Flyway – Northwest
(17.4%), Mississippi Flyway – Gulf Coast (16.2%),
Mexico (13.5%), and Central Flyway Low Plains – South
(11.1%) were the most important minor harvest areas for
immature male BWTE (Table 4).
Immature females.—The Mississippi Flyway (44.7%),
Latin America (28%), and the Central Flyway (13.5%)
were the most important major harvest areas for
immature female BWTE. Mississippi Flyway –
Northwest (19.4%), Mississippi Flyway – Gulf Coast
(17.2%), and Mexico (12.7%) were the most important
minor harvest areas for immature female BWTE
(Table 5).
Derivation of the Blue-winged Teal
Harvest from Breeding Reference
Areas, 1970 – 2003
All age/sex classes
The Eastern Dakotas BRA contributed the most
(29.8%) to the total BWTE harvest for all years.
Blue-winged Teal from the Eastern Saskatchewan/
Southwestern Manitoba (16.9%), Upper Midwest
(12.1%), and Western Saskatchewan (11.0%) BRAs
were also important contributors to the total BWTE
harvest from 1970 – 2003 (Table 6).
Canada
Alberta.—Alberta is on the northern and western
portion of the BWTE primary breeding range. It is
not surprising to find that Southern Alberta (51%)
and Central Alberta (36.8%) were the most important
BRAs for BWTE harvest in Alberta (Table 6, Fig. 39).
Saskatchewan.—Western Saskatchewan (43.1%) and
Eastern Saskatchewan/Southwest Manitoba (37.2%)
were the most important BRAs determining BWTE
harvest in this province (Table 6, Fig. 40).
ReNsualtms aen do fD Siseccutsisoionn 31
Table 2. Distribution of the adult male Blue-winged Teal harvest, 1970 – 2003.
Manitoba.—Eastern Saskatchewan/Southwest
Manitoba (49.2%) and West-central Manitoba (41.3%)
were the most important BRAs determining BWTE
harvest in Manitoba (Table 6, Fig. 41).
Ontario.—Blue-winged Teal harvest in this province
was most dictated by birds coming from the U.S.
Great Lakes (41.6%) and Eastern Ontario/Southern
Quebec (36.4%) BRAs (Table 6, Fig. 42).
Quebec.—Quebec (51.4%) and Eastern
Saskatchewan/Southwest Manitoba (13.5%) were the
most important BRAs determining harvest in this
province (Table 6, Fig. 43).
Maritimes Provinces.—This area derived much of its
BWTE harvest from the Maritimes/Maine (30.3%) BRA.
Eastern Ontario/Southern Quebec (19.8%), Eastern
Saskatchewan/Southwest Manitoba (19.2%), and U.S.
Great Lakes (12.2%) BRAs were also important in
determining harvest for this area (Table 6, Fig. 44).
Pacific Flyway
Less than 1% of the total BWTE harvest occurs in this
flyway and the percentages are based on relatively few
actual band recoveries (n = 79; Table 6).
32 Distribution and Derivation of the Blue-winged Teal Harvest
Table 3. Distribution of the adult female Blue-winged Teal harvest, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 33
Table 4. Distribution of the immature male Blue-winged Teal harvest, 1970 – 2003.
34 Distribution and Derivation of the Blue-winged Teal Harvest
Table 5. Distribution of the immature female Blue-winged Teal harvest, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 3355
Table 6. Derivation of the Blue-winged Teal harvest for all age/sex classes, 1970 – 2003.
36 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 39. Derivation of Blue-winged Teal harvested in Alberta (shaded) based on direct recoveries
	
(n = 140) of all age/sex classes, 1970 – 2003.
Figure 40. Derivation of Blue-winged Teal harvested in Saskatchewan (shaded) based on direct recoveries
	
(n = 162) of all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 37
Figure 41. Derivation of Blue-winged Teal harvested in Manitoba (shaded) based on direct recoveries
	
(n = 236) of all age/sex classes, 1970 – 2003.
Figure 42. Derivation of Blue-winged Teal harvested in Ontario (shaded) based on direct recoveries
	
(n = 1,114) of all age/sex classes, 1970 – 2003.
3388 D iDstisrtibriubtuiotnio nan adn dD eDreivraivtaiotnio nof o tfh teh Be lBuleu-ew-iwnignegde dT eTael aHl Haravrevsetst
Figure 43. Derivation of Blue-winged Teal harvested in Quebec (shaded) based on direct recoveries (n = 536)
of all age/sex classes, 1970 – 2003.
Figure 44. Derivation of Blue-winged Teal harvested in the Maritimes (shaded) based on direct recoveries
	
(n = 613) of all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 3399
Pacific Flyway – North.—Four BRAs contributed
relatively equally to harvest of BWTE in this area:
Central Alberta (25.5%); Southern Alberta (29.1%);
Western Saskatchewan (22.1%); and Northern Great
Plains BRAs (23.3%; Table 6, Fig. 45).
Pacific Flyway – South.—The Eastern Dakotas
(29.8%) was the most important BRA in determining
harvest in this area. However, Northern Great
Plains (21.5%), Southern Alberta (20.7%), and
Central Alberta (19.7%) were also important BRAs
for this harvest area (Table 6, Fig. 46).
Central Flyway
Central Flyway High Plains – North.—The
Northern Great Plains (43.9%) and Eastern
Dakotas (31.7%) were the most important BRAs in
determining BWTE harvest in this area (Table 6,
Fig. 47).
Central Flyway Low Plains – North.—The Eastern
Dakotas (58.5%) and Eastern Saskatchewan/
Southwest Manitoba (16.7%) were the most
important BRAs for determining harvest for this
area (Table 6, Fig. 48).
Central Flyway High Plains – South.—This
harvest area received large portions of its BWTE
from several BRAs: Western Saskatchewan (25%);
Northern Great Plains (22.5%); Central Alberta
(15.3%); Eastern Dakotas (14.3%); Eastern
Saskatchewan/Southwestern Manitoba (10.3%); and
Southern Alberta BRAs (9.9%; Table 6, Fig. 49).
Central Flyway Low Plains – South.—The
Eastern Dakotas (44.3%), Eastern Saskatchewan/
Southwestern Manitoba (15.6%), and Western
Saskatchewan (12.8%) were the most important
BRAs in determining this area’s BWTE harvest
(Table 6, Fig. 50).
Mississippi Flyway
Mississippi Flyway – Northwest.—The Upper
Midwest (38%), Eastern Dakotas (24.9%), Eastern
Saskatchewan/Southwestern Manitoba (13.8%),
and West-central Manitoba (11.2%) were the most
important BRAs in dictating BWTE harvest in this
important harvest area (Table 6, Fig. 51).
Mississippi Flyway – Northeast.—The Eastern
Dakotas (33.1%), Upper Midwest (16.3%), Eastern
Saskatchewan/Southwestern Manitoba (15.4%), and U.S.
Great Lakes (15.3%) were the most important BRAs for
harvest of BWTE in this area (Table 6, Fig. 52).
Mississippi Flyway – West-central.—The Eastern
Dakotas (33%), Eastern Saskatchewan/Southwestern
Manitoba (21.7%), Upper Midwest (12.8%), and
Western Saskatchewan (12.5%) were the most
important BRAs for harvest in this area (Table 6,
Fig. 53).
Mississippi Flyway – South.—The Eastern Dakotas
(31.7%), Eastern Saskatchewan/Southwestern
Manitoba (19.1%), Upper Midwest (13.3%), and Western
Saskatchewan (13.6%) were the most important BRAs
for harvest in this area (Table 6, Fig. 54).
Mississippi Flyway – Gulf Coast.—The Eastern
Dakotas (41.2%), Eastern Saskatchewan/
Southwestern Manitoba (19.1%), and Western
Saskatchewan (11.7%) were the most important
BRAs for this high harvest area for BWTE (Table 6,
Fig. 55).
Atlantic Flyway
Atlantic Flyway – North.—Eastern Ontario/
Southern Quebec (28%), Eastern Dakotas
(19.2%), Northeast States (16.4%), and Eastern
Saskatchewan/Southwest Manitoba (12%) were the
most important BRAs for BWTE harvest in this area
(Table 6, Fig. 56).
Atlantic Flyway – Central.—This was the only
harvest area where the Northeast States BRA
(29.1%) was the most important BRA for dictating
harvest. Other important BRAs for this harvest area
were the Eastern Dakotas (24.5%) and U.S. Great
Lakes BRAs (12.8%; Table 6, Fig. 57).
Atlantic Flyway – South.—The Eastern Dakotas
(27.8%), Eastern Saskatchewan/Southwestern
Manitoba (19.4%), and Upper Midwest (15.2%) were
the most important BRAs in determining BWTE
harvest in this area (Table 6, Fig. 58).
Latin America
Mexico.—Several BRAs contributed heavily to this
country’s BWTE harvest: Northern Great Plains
(19.7%); Eastern Dakotas (19.4%); Central Alberta
(16.9%); Western Saskatchewan (16.5%); and Eastern
Saskatchewan/Southwestern Manitoba BRAs (15.2%;
Table 6, Fig. 59).
Central America.—Several BRAs contributed
heavily to this region’s BWTE harvest: Eastern
Dakotas (22.8%); Central Alberta (20.5%); Eastern
Saskatchewan/Southwestern Manitoba (20%); and
Western Saskatchewan BRAs (16.2%; Table 6, Fig. 60).
South America.—Several BRAs contributed
heavily to BWTE harvest on the northern tier of
this continent: Eastern Dakotas (25.7%); Eastern
Saskatchewan/Southwestern Manitoba (17%); Upper
Midwest (14.6%); Western Saskatchewan (13.7%);
and Central Alberta BRAs (10%; Table 6, Fig. 61).
Caribbean Countries.—Many BRAs contributed to
this region’s BWTE harvest; however, the Eastern
Dakotas (27.9%) and Eastern Saskatchewan/
Southwestern Manitoba (20.8%) BRAs were the most
important for determining BWTE harvest in the
region (Table 6, Fig. 62).
40 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 45. Derivation of Blue-winged Teal harvested in the northern Pacific Flyway (shaded) based on direct
recoveries (n = 11) of all age/sex classes, 1970 – 2003.
Figure 46. Derivation of Blue-winged Teal harvested in the southern Pacific Flyway (shaded) based on direct
recoveries (n = 68) of all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 41
Figure 47. Derivation of Blue-winged Teal harvested in the northern portion of the Central Flyway High
Plains Unit (shaded) based on direct recoveries (n = 84) of all age/sex classes, 1970 – 2003.
Figure 48. Derivation of Blue-winged Teal harvested in the northern portion of the Central Flyway Low
Plains Unit (shaded) based on direct recoveries (n = 360) of all age/sex classes, 1970 – 2003.
42 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 49. Derivation of Blue-winged Teal harvested in the southern portion of the Central Flyway High
Plains Unit (shaded) based on direct recoveries (n = 147) of all age/sex classes, 1970 – 2003.
Figure 50. Derivation of Blue-winged Teal harvested in the southern portion of the Central Flyway Low
Plains Unit (shaded) based on direct recoveries (n = 1,732) of age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 4433
Figure 51. Derivation of Blue-winged Teal harvested in the northwest portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 2,236) of all age/sex classes, 1970 – 2003.
Figure 52. Derivation of Blue-winged Teal harvested in the northeast portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 393) of all age/sex classes, 1970 – 2003.
44 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 53. Derivation of Blue-winged Teal harvested in the west-central portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 501) of all age/sex classes, 1970 – 2003.
Figure 54. Derivation of Blue-winged Teal harvested in the southern portion of the Mississippi Flyway
(shaded) based on direct recoveries (n = 458) of all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 45
Figure 55. Derivation of Blue-winged Teal harvested in the Gulf Coast region of the Mississippi Flyway
(shaded) based on direct recoveries (n = 2,854) of all age/sex classes, 1970 – 2003.
Figure 56. Derivation of Blue-winged Teal harvested in the northern portion of the Atlantic Flyway (shaded)
based on direct recoveries (n = 621) of all age/sex classes, 1970 – 2003.
46 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 57. Derivation of Blue-winged Teal harvested in the central portion of the Atlantic Flyway (shaded)
based on direct recoveries (n = 294) of all age/sex classes, 1970 – 2003.
Figure 58. Derivation of Blue-winged Teal harvested in the southern portion of the Atlantic Flyway (shaded)
based on direct recoveries (n = 592) of all age/sex classes, 1970 – 2003.
Name of Section 47
Results and Discussion 47
Figure 59. Derivation of Blue-winged Teal harvested in Mexico (shaded) based on direct recoveries (n = 714)
of all age/sex classes, 1970 – 2003.
Figure 60. Derivation of Blue-winged Teal harvested in Central America (shaded) based on direct recoveries
(n = 277) of all age/sex classes, 1970 – 2003.
48 Distribution and Derivation of the Blue-winged Teal Harvest
Figure 61. Derivation of Blue-winged Teal harvested in South America (shaded) based on direct recoveries
(n = 398) of all age/sex classes, 1970 – 2003.
Figure 62. Derivation of Blue-winged Teal harvested in the Caribbean (shaded) based on direct recoveries
	
(n = 612) of all age/sex classes, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 49
All harvest areas by age/sex class
Adult males.—The Eastern Dakotas BRAs
contributed the most (29.6%) to the total adult male
BWTE harvest for all years. Adult male BWTE from
Eastern Saskatchewan/Southwestern Manitoba (16%),
Western Saskatchewan (12.3%), and Upper Midwest
(12.2%) BRAs were also important contributors to the
harvest from 1970 – 2003 (Table 7).
Adult females.—The Eastern Dakotas BRA
contributed the most (29.8%) to the total adult female
BWTE harvest for all years. Adult female BWTE
from Eastern Saskatchewan/Southwestern Manitoba
(15.4%), Upper Midwest (14.3%), and Western
Saskatchewan (11%) BRAs were also important
contributors to the harvest from 1970 – 2003 (Table 8).
Immature males.—The Eastern Dakotas BRA
contributed the most (29.6%) to the total immature
male BWTE harvest for all years. Immature male
BWTE from Eastern Saskatchewan/Southwestern
Manitoba (19.5%), Upper Midwest (11.1%), and
Western Saskatchewan (10.8%) BRAs were also
important contributors to the harvest from 1970 –
2003 (Table 9).
Immature females.—The Eastern Dakotas BRA
contributed the most (30.2%) to the total immature
female BWTE harvest for all years. Immature
female BWTE from Eastern Saskatchewan/
Southwestern Manitoba (16%), Upper Midwest
(11.9%), and Western Saskatchewan (10.3%) BRAs
were also important contributors to the harvest from
1970 – 2003 (Table 10).
Changes in Distribution of the Blue-winged
Teal Harvest
between Time Periods
Distribution of the BWTE harvest by time period can
be found in Appendices (D – G). Below are changes
that we felt were more pronounced than others. We
did not make comparisons to harvest survey data
collected over the same time period because data
from Latin America is sparse or non-existent, and
USFWS and Canadian Wildlife Service harvest
estimates based on the parts collection survey cannot
discriminate between BWTE and Cinnamon Teal,
biasing BWTE harvest estimates upward in the
Pacific Flyway.
The proportion of the BWTE harvest during the
1994 – 2003 time period that was distributed to
Latin American countries (18.6%) was substantially
lower than that observed during 1970 – 1979, 1980
– 1986, and 1987 – 1993 (36.7%, 25.6%, and 36.8%,
respectively). It is possible that the distribution
of harvest to Latin America had a steady linear
downward trend over the four time periods. However,
closure of September teal seasons in the U.S. during
four of the seven years during the 1987 – 1993 time
period may have resulted in much of the harvest being
re-distributed to Latin America, perhaps resulting in
the non-linear results. South America represented
somewhat low (<3.3%) proportions of the total harvest,
with the exception of the 1970 – 1979 (7.5%) and
1987 – 1993 (13%) time periods. Proportional BWTE
harvest in Mexico, while remaining high, has declined
from 16.9% during the 1970 – 1979 time periods to 8%
during the 1994 – 2003 time periods in a somewhat
linear fashion. Kramer et al. (1995) speculated that
waterfowl harvests in Mexico had been declining
for some time due to increased prices of firearms,
ammunition, and hunting licenses, to the increased
difficulty for American citizens to hunt in Mexico, and
to greatly reduced habitat due to Hurricane Gilberto
in the mid-1980s. As we have documented here, aside
from the increase in South America’s take of the total
harvest during 1987 – 1993, the trend among the
four time periods for Latin America’s portion of the
harvest appears to be a decline with the largest decline
occurring post-1993. This may be the result of BWTE
harvest being re-distributed back to U.S. harvest areas
with resumption of the 9-day September teal seasons
in 1992, and beginning in 1998, 16-day September teal
seasons.
Another potential explanation for the most recent
decline in Latin America’s proportional take in the
BWTE harvest could be temporal heterogeneity in
band-reporting rates that differ from those in the
U.S. Band-reporting rates in the U.S. increased
substantially following initial deployment (ca. 1995) of
bands inscribed with a toll-free telephone number for
hunters to call to report bands (Royle and Garrettson
2005). We assumed a constant differential reduction in
reporting rates in Latin America that was one-half of
U.S. reporting rates. If, in reality, band-reporting rates
did not increase in Latin America, distribution of the
harvest to this region would have been underestimated.
There were concerns that hunters attempting to report
bands in Latin America initially had difficulty using
the toll-free telephone number that was inscribed
on bands. As a result, a separate operating system
was implemented to handle recoveries in Mexico (J.
Haskins, pers. comm.). However, the ineffectiveness of
toll-free bands at increasing band-reporting rates likely
would have been muted somewhat, because a portion of
the harvest in many areas of Latin America is taken by
U.S. citizens who had the opportunity to report bands
upon re-entering the U.S.
Changes in Derivation of the
Blue-winged Teal Harvest
between Time Periods
The Eastern Dakotas BRA has maintained a strong
contribution to the harvest of BWTE during all time
periods (17.3% – 42.6%; Appendices H – K). This
region was the most important BRA for BWTE in
all time periods except 1987 – 1993, when the U.S.
prairies experienced extreme drought conditions.
Mid-summer rains beginning in 1993 ended the
50 Distribution and Derivation of the Blue-winged Teal Harvest
Table 7. Derivation of the adult male Blue-winged Teal harvest, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 51
Table 8. Derivation of the adult female Blue-winged Teal harvest, 1970 – 2003.
52 Distribution and Derivation of the Blue-winged Teal Harvest
Table 9. Derivation of the immature male Blue-winged Teal harvest, 1970 – 2003.
ReNsualtms aen do fD Siseccutsisoionn 53
Table 10. Derivation of the immature female Blue-winged Teal harvest, 1970 – 2003.
54 Distribution and Derivation of the Blue-winged Teal Harvest
Flyway – West-central that is derived from the
West-central Manitoba BRA declined sharply in
the two most recent time periods (9.6% and 11.9%
during 1970 – 1979 and 1980 – 1986, respectively, to
1.7% and 2.6% during 1987 – 1993 and 1994 – 2003,
respectively; Appendices H – K).
Grouping Breeding
Reference Areas
for Future Analyses
We defined BRAs at spatial scales that we felt would
be of interest for waterfowl managers across North
America. Using BRAs at relatively small spatial
scales for distribution and derivation of the harvest
required that we pool data from multiple years
and age/sex classes. Other analyses, particularly
survival analyses, generally require data that are
parsed annually and by age/sex class. Grouping
some BRAs in a north-to-south fashion will also
alleviate violations of assumptions pertaining to
origins of BWTE, particularly those ignoring
the early migration strategy of this species. For
example, many adult male BWTE begin migration
in mid to late-August, and undoubtedly, are banded
south of the BRA from which they departed. Our
recommendation to pool certain BRAs is also
important from the standpoint of including habitat
covariates in other analyses. Ideally, particularly
from a habitat covariate standpoint, BRAs would
not need to be grouped into larger breeding regions;
however, reduced sample sizes due to significant
gaps in banding in some BRAs will necessitate some
grouping.
A well-defined split occurs in the distribution and
derivation of the BWTE harvest relative to BRAs
east and west of 87°W. Using these two groups
should be the coarsest that BWTE banding data
are analyzed. However, finer groupings can occur,
provided sufficient banding and recovery data is
available. Blue-winged Teal bandings and recoveries
from the Central Alberta, Southern Alberta, Western
Saskatchewan, and Northern Great Plains BRAs
should be grouped as the Western Prairies BWTE
breeding region. Blue-winged Teal bandings
and recoveries from the Eastern Saskatchewan/
Southwestern Manitoba, Eastern Dakotas, West-central
Manitoba, and Upper Midwest BRAs
should be combined as the Eastern Prairies BWTE
breeding region. The most important distinction
between these two breeding regions is their
contributions to harvest in Mexico, Central America,
and the Mississippi Flyway – Northwest. Ideally,
the Upper Midwest BRA would be maintained as
its own breeding region, given the unique harvest
distribution of BWTE from within its borders,
relatively large geographic size, and representation
of both large expanses of prairie and forest and
associated ecotone. Unfortunately, large annual
variation and occasional lack of preseason BWTE
bandings within this BRA preclude its ability to
drought in the Eastern Dakotas BRA, and initiated
an unprecedented wet-cycle that continued until
the mid-2000s (Fig. 8). Superb breeding conditions
in the Eastern Dakotas BRA persisted upon the
return of excellent wetland conditions, coupled with
1.2 – 1.4 million ha (3 – 3.5 million ac) of large blocks
of undisturbed perennial grass provided by the
Conservation Reserve Program which has provided
secure nesting habitat. As a result, 42.6% of the total
BWTE harvest originated in the Eastern Dakotas
BRA during the 1994 – 2003 time period. Although,
as previously mentioned, some birds banded in the
Eastern Dakotas BRA likely are early migrants from
Canada, this does not account for the doubling of the
percentage of BWTE harvest that originated in the
Eastern Dakotas BRA from previous time periods.
Extreme drought conditions in the Eastern Dakotas
BRA during the 1987 – 1993 time periods appeared to
significantly affect derivation of the BWTE harvest
in the southern Central Flyway Low Plains.
Percentage of the harvest in the southern Central
Flyway Low Plains derived from the Eastern Dakotas
BRA dropped from 35.7% and 46.4% during the 1970
– 1979 and 1980 – 1986 time periods, respectively,
and to 25.3% during 1987 – 1993 (Appendices H – K).
Conversely, contribution to the BWTE harvest in
the southern Central Flyway Low Plains from the
Eastern Dakotas BRA rebounded considerably to
53.3% during the 1994 – 2003 time period.
The contribution of 2 BRAs declined substantially
during the 1994 – 2003 time period from prior the
time periods. Percentage of the BWTE harvest
derived from the Central Alberta BRA decreased
from 8.7%, 12.4%, and 14.1% during the 1970 –
1979, 1980 – 1986, and 1987 – 1993 time periods,
respectively, to 4.8% during the 1994 – 2003 time
period. Similarly, percentage of the BWTE harvest
derived from the West-central Manitoba BRA
decreased from 7.9%, 7.9%, and 6.1% during the
1970 – 1979, 1980 – 1986, and 1987 – 1993 time
periods, respectively, to 3.1% during the 1994 – 2003
time period (Appendices H – K). These decreases
in contribution are coincident with ideal breeding
conditions in the Eastern Dakotas BRA, which
likely attracted breeding BWTE away from these
other areas, particularly given the nomadic nature
of breeding area selection by BWTE (Johnson and
Grier 1988). However, the two aforementioned
Canadian BRAs have also endured serious wetland
losses over the years through drainage and
subsequent conversion to agriculture, and frequent
drought in western areas (Khandekar 2004).
The derivation of BWTE harvest from the West-central
Manitoba BRA in several minor harvest
areas has shown substantial declines over time. The
percentage of BWTE harvest in the Mississippi
Flyway – Northwest that is derived from the West-central
Manitoba BRA has declined steadily over the
four time periods (16.7% during 1970 – 1979 to 4.2%
during 1994 – 2003; Appendices H – K). Similarly,
the percentage of BWTE harvest in the Mississippi
ReNsualtms aen do fD Siseccutsisoionn 55
be used individually for survival analyses. Finally,
BWTE bandings and recoveries originating from
all areas east of 87°W (i.e., the U.S. Great Lakes,
Eastern Ontario/Southern Quebec, Maritimes/Maine,
and Northeast States BRAs) should be grouped to
form the Eastern BWTE breeding region. This
breeding region is much larger in size than desired,
but small sample sizes of banded birds preclude
separating distinct breeding regions east of 87°W
where all BRAs could remain separate, with the
exception of the combination of the Maritimes/Maine
and Northeast States BRAs.
Bi-weekly Harvest
of Blue-winged Teal
Managers are often interested in the progression of
the BWTE harvest through time as well as across
geographic regions. Harvest opportunities for
BWTE progress in a somewhat bifurcated fashion
during the first two months of waterfowl hunting
seasons. Duck hunting seasons in western Canadian
provinces generally open the first of September and
September teal seasons generally open the second
Saturday of September in teal non-breeding U.S.
states. Teal harvest occurs primarily in Canada and
states south of about 43°N in much of September
(Appendices L and M). Duck hunting seasons then
open in northern breeding areas of the U.S. and
eastern Canadian provinces during the last week of
September, sometimes slightly overlapping (usually
a weekend) with September teal seasons in southern
states. As a result, the relative harvest density
increases dramatically in the northern U.S. states,
although relatively high numbers of teal still are
taken in some areas of the Gulf Coast (Appendices N
and O). From the end of October through November,
December, and finally January when hunting seasons
in the U.S. close, harvest density is highest in the
so