Waterfowl production and habitat survey for South and North Dakota

              2001
WATERFOWL PRODUCTION SURVEY
FOR
SOUTH DAKOTA AND NORTH DAKOTA
Williston
Dickinson
Garrison
Bismarck
Minot Devils Lake
Grand
Forks
Jamestown Fargo
Aberdeen
Water-town
Sioux Falls
Madison
Huron
Mitchell
Pierre
Camp Crook Mobridge
Belle Fourche
Rapid City
49
44 48
46
43 47
45
TITLE: Waterfowl Production and Habitat Survey for South and North
Dakota
STRATA SURVEYED: 44, 48, 49 (South Dakota)
43, 45, 46, 47, 48 (North Dakota)
DATES: 3 - 18 July 2001
DATA SUPPLIED BY: United States Fish and Wildlife Service
Strata 45, 46, 47, 48, 49
Observer/Pilot - John W. Solberg, Flyway Biologist,
DMBM/WPS, USFWS, Bismarck, ND
Observer - Sue Thomas, Secretary, MBHP, USFWS, Portland, OR
Strata 43 and 44
Observer/Pilot - James F. Voelzer, Chief - DMBM/WPS, USFWS,
Portland, OR
Observer - Ray Bentley, Flyway Biologist, DMBM/WPS,
Corvallis, MD
ABSTRACT: The 2001 Waterfowl Production and Habitat Survey for eastern South and North
Dakota was conducted during 3 - 18 July. Survey procedures in 2001 were unchanged but
traditional coverage was incomplete. Weather patterns in June and July encouraged excellent
stands of wetland basin and upland cover. June precipitation was more beneficial to North
Dakota habitat than that in South Dakota. Wetland counts were similar or decreased slightly in
the Dakotas compared to July of 2000 (SD 6%, ND -16%) but remain significantly above long-term
averages (SD 30%, ND 52%). The Duck Brood Index (DBI) in South Dakota (89.7) is the
seventh highest of record and is similar to the ten-year average. In North Dakota, the 2001 DBI
(173.8) is fourth highest of record and although decreased (-20%) compared to 2000, is above
the ten-year mean (46%). The 2001 brood indices are well above the long-term averages in both
states (SD 99%, ND 192%). The total duck late nesting index (LNI) in South Dakota increased
132% compared to 2000, is below (-18%) the ten-year average, and similar to the long-term
mean (10%). LNI in North Dakota was below the respective 2000, ten-year, and long-term
figures (-23%, -45%, and -56%).
METHODS: The procedures followed in conducting the 2001 waterfowl production survey are
described in the Standard Operating Procedures (SOP) for Aerial Waterfowl Breeding Ground
Population and Habitat Surveys in North America, Section IV, revised 1987. Initially, aerial
observations were recorded using two laptop computers which were interfaced with the aircraft
GPS. On the fifth day of the survey, one of the units failed, forcing the observer to revert to a
tape recorder for recording observations. No other changes occurred this year in operational
procedures but survey coverage was incomplete. Due to a tape recorder malfunction,
observations from three segments in Stratum 45 were missing from the right side of the aircraft.
Additionally, a post survey examination of Stratum 48 data revealed eight segments missing
from the left side of the aircraft. Improper computer file management disallowed retrieval of the
missing data. To adjust the expansion factor, those segments with incomplete data (one side of
the aircraft missing) were removed from the data set and new expansion factors were calculated.
These adjustments are indicated in Tables 4 and 8. In the crew area, 2001 marked the first
waterfowl production survey for the right seat observer. Sue Thomas had assisted in conducting
the Waterfowl Breeding Population survey earlier in the year. All survey data reported in 2001
are considered comparable to earlier years. Transects in the Western Dakotas (strata 43 and 44)
were completed by the Montana survey crew led by James Voelzer. Our appreciation is
extended to the Montana crew for their help. Transect flying began in eastern South Dakota on 3
July and was completed in North Dakota on 18 July. One day of survey flying was lost to
inclement weather (thunderstorm/hail/wind) and on another day, only one segment was
completed because of fog. Survey time parameters, outlined in the SOP, were violated during
five days of sampling. On these days, foggy conditions lasting into the late morning forced us to
survey later than the noon cut-off specified in the SOP. All survey flights were completed in N-
761, a wheeled Cessna 185. Required flight time was about 65 hours.
WEATHER AND HABITAT CONDITIONS:
June began in South Dakota with cooler temperatures (1-3 degrees below normal) and rainy
weather throughout most of the state. In fact, soil and crop conditions were reported as favorably
to abnormally moist throughout South Dakota in June. The second week brought scattered
severe weather. Most stations reported an inch or more precipitation with Huron reporting the
least of .44 inches. Severe weather increased during the third week of June with hail, damaging
winds and thunderstorms. Huron received the opposite extreme in precipitation than the rest of
the state with 4.13” reported. Again, most stations received an inch of rain. Warmer conditions
and sunshine brought the month to a close, increasing cover growth but promoted the drying of
wetlands. Precipitation levels dropped to a minimum with some stations reporting zero
precipitation.
North Dakota experienced similar weather patterns with soil and crop conditions remaining at
favorably to abnormally moist throughout the month. Temperatures during the first week of
June averaged 5 degrees below normal and precipitation levels were considered moderate. A
strengthening low situated over the central plains produced approximately 10 days of unsettled
weather including: severe thunderstorms, damaging hail and high winds. Temperatures remained
below normal and precipitation continued through the third week. Overall, temperatures for the
first three-quarters of the month were 2-7 degrees below normal. In late June, temperatures
moderated, encouraging rapid development of crops and upland/basin cover.
Normal temperatures arrived in both states during the first week of July. Generally, little
precipitation was received over the region with one exception. Reporting stations in south
central Stratum 48 and 49 received .5 to over 2" of rain during that period. The second week of
July, temperatures elevated to above normal. Precipitation in “east river” areas was light.
During the remainder of the survey, above normal temperatures and high humidity caused early
morning fog which usually “improved” to haze. These conditions were conducive for cumulus
build-up with thunderstorms occurring mid-morning and through the remainder of the day.
Considering the fact that wet conditions returned to the Dakota prairies in July of 1993, 2001
marks the ninth consecutive year of above average, statewide wetland counts. The duration of
this wet cycle must certainly have nutrient and invertebrate levels below maximum potential in
many basins.
SOUTH DAKOTA (St. 48/49: 3 - 9 July)
Wetland counts statewide increased slightly (6%) in South Dakota compared to 2000 (Table 3).
The July index decreased -55% since the May survey and the ten-year average (-13%), but is
30% wetter than the long-term average (LTA).
Stratum 44 - The west river crew reported that precipitation received since the May survey
resulted in lush and extensive upland and riparian cover. All habitat in the stratum was
considered good except a small area in the central portion (considered fair) which apparently
received less rain. Stratum 44 was the only South Dakota survey unit where wetland counts
increased (39%) since the May survey. The 2001 index (146.8) was similar to the July 2000
figure (-9%), fell short (-16%) of the ten-year mean, and was 16% above the long-term average.
Stratum 48 - Wetland counts in Stratum 48 declined -65% since May. The stratum index was
similar to the July 2000 figure (8%), slightly drier than the ten-year mean (-12%), but 42% above
the LTA. In the Prairie Coteau, the Leola Hills, and a narrow area running from Mitchell to just
west of Huron, we considered nesting/brooding habitat excellent. Here, semi-permanent and
permanent basins were full to overflowing and some seasonal wetlands still existed. Throughout
the remainder of the stratum, seasonal water was absent. Type IV and V wetlands along with
dugouts were nearly full to slightly recessional. In these areas, we considered the habitat good.
Wetland basin and upland cover was excellent in all areas.
Stratum 49 -In Stratum 49, wetland numbers dropped -68% since the May survey. Although the
2001 figure was slightly below the ten-year average (-9%), conditions were 29% wetter than July
2000 and 32% on the positive side of the LTA. In the Prairie Coteau region of the north, and a
small area in south central Stratum 49, some Type III water did exist. Coupled with brimming
water levels in Type IV and Type V basins, we considered conditions in these areas excellent.
As in May, the south east region (surrounding Sioux Falls) was a bit drier than other areas of the
state and considered in fair condition. Because of drier conditions agriculture had their typically
strong foothold and some basins had been tilled or hayed. The remainder of the stratum
exhibited little or no seasonal water but the more permanent basins, for the most part, were
nearly full or only slightly recessional.
NORTH DAKOTA (St. 45/46/47: 10 - 18 July)
Total wetland counts in North Dakota decreased only -15% since the May 2001 survey. The
2001 index dropped -16% compared to the July 2000 figure and is unchanged from the ten-year
average. The index is 52% above the long-term mean (Table 7).
Stratum 43 - West river North Dakota too, benefitted from June rainfall. Again, upland and
emergent vegetation growth was lush and extensive, but not as thick as in South Dakota.
Conditions in the majority of Stratum 43 were considered good except for the extreme north west
portion which was only fair. The wetland index for July 2001 increased 52% since the May
survey and is 31%, 18%, and 51% above last July’s index, the ten-year mean, and the long-term
average.
Stratum 45 - Wetland counts in Stratum 45 decreased a mere -19% since May. The 334,200
wetlands fell short of the July 2000 index (-20%), but was similar to the ten-year average (5%)
and well above the LTA (59%). Beneficial June precipitation actually improved conditions
(from good to excellent) in northern and southern reaches of the Missouri Coteau and maintained
the excellent conditions that surrounded Devils Lake in May. Some drying did occur in the
northwest, increasing the size of the “fair” area reported in May. Additionally, a small area in
the extreme north east corner was considered only fair. The remainder of the stratum was
considered in good condition.
Stratum 46 - Wetlands recorded during the survey in 46 decreased -28% since May of this year.
The 2001 July figure was below that of 2000 (-27%) and the ten-year average (-16%) but 48%
above the long-term average. As in Stratum 45, conditions in the Missouri Coteau portions of
Stratum 46 improved to excellent as a result of June precipitation. The area in the south east
region also maintained its excellent habitat condition. The remainder of the stratum was classed
as good brood rearing and late nesting habitat.
Stratum 47 - The wetland index in Stratum 47 decreased compared to May (-54%), the 2000
index (-37%), and the ten-year average (-36%). The 2001 figure was similar to the LTA (-8%).
All four habitat condition classifications occurred in Stratum 47 this July. The northern 1/3 is in
fair/poor condition. More than half (eastern) of nearly all of the southern 2/3rds is also
considered fair. A tiny portion in the southern tip, protruding in from Stratum 46, was excellent.
This area was south of the historic Lake Agassiz lake bed. The remainder of 47 was considered
good.
Production Indices: Perfect correlation between waterfowl breeding population and brood indices
seldom occur. It is logical though that trends should be somewhat similar. In May of 2001,
South Dakota held its second highest waterfowl breeding population of record and in North
Dakota, the breeding population was third highest. Brood indices do not rank exactly with
breeding populations but production, compared to over forty years of survey, was again strong.
The DBI in South Dakota ranks seventh highest of record at 89,700 broods. The index decreased
-22% compared to last year, is similar to the ten-year average (5%), and well above (99%) the
long-term mean (Table 2). Examination of DBI’s by stratum since 2000 (see report) reveals the
most significant decrease in production (-47%) in Stratum 44. The brood index is Stratum 49
decreased -23% but with the small sample, the decrease represents only 2,600 broods.
Production in Stratum 48 was unchanged since last year (-2%). Production figures in 48 and 49
might be explained by the larger than “normal” decrease in wetland numbers (-65% to -68%)
since May, but in 44 the large decrease in the DBI is somewhat baffling. July 2001 wetland
counts were similar to those from last year (-9%), yet from May to July of 2001, wetland
numbers actually increased 39%. The statewide DBI for 2001 is similar though to those indices
recorded during the current wet cycle. Average brood size in South Dakota in 2001 is similar to
the three standard time comparisons (2%, -5%, and 6%). Coot production rebounded from last
year (up 50%), fell short of the ten-year mean (-22%), and is above the LTA (72%).
In North Dakota, the DBI (173.8) decreased -20% since 2000 (Table 6). Increases occurred
when compared to the ten-year average (46%) and the long-term average (192%). Comparing
2001 DBI’s by stratum to the indices from 2000 (see report), suggest similar production from
stratum 43 (-5%) and 45 (-2%), but a significant decline (-42%) in Stratum 46 (where wetland
counts were nearly -30% lower than last year). A 67% increase in the DBI occurred in Stratum
47, but again the sample size is small and the increase represents only 1,400 broods. Average
brood size in North Dakota was similar to last year (-6%) and the long-term mean (-7%) but was
-15% below the ten-year average. The coot brood index in North Dakota decreased -50%
compared to 2000 and -29% compared to the ten-year average. Coot broods for 2001 were 85%
above the LTA.
As always, we believe our DBI’s are conservative. The right seat observer was inexperienced
conducting brood surveys prior to this effort. Wetland vegetation was extremely heavy and
greatly reduced our ability to see broods. This condition was further aggravated at wetland
basins in recessional condition, where lower water levels increased the amount of exposed
vegetation and created more “hiding places.” Although winds were generally light during
survey, we were forced to violate established sampling time parameters because of late morning
fog which delayed our departure. Lastly, the proportion of observed/actual broods present
remains unknown without the luxury of ground truthing. To put 2001 production in perspective,
during the dry years of 1990 and 1991, 30 broods recorded by the aerial crew during an average
day of sampling (16 - 18 segments) was a “good” day. This year our highest one day brood
counts were 196 in South Dakota and 212 in North Dakota.
It appears that again, above average waterfowl breeding populations have experienced
production well above long-term levels.
Late Nesting Indices: The Late Nesting Index is intended as a relative measure of late or
secondary nesting effort. (Tables 1 and 5). In South Dakota, total LNI increased 132% compared
to last year. The indicated effort by Mallards was particularly strong in all strata. This
indication seems logical in Stratum 44 where wetland counts increased since May. In 48 and 49,
wetland numbers diminished more than “normal” since the May survey, yet the Mallard LNI
increased significantly since last year (see 2000 report).
Conversely, in North Dakota total LNI was below last year’s level (-23%), and the ten-year
(-45%) and long-term (-56%) averages. North Dakota benefitted more from June precipitation as
reflected in the comparison of May and July wetland counts. It is possible that because of more
stable water conditions (compared to South Dakota), initial nesting attempts in North Dakota
were more successful. A reduced LNI could result from this scenario.
Conclusions:
1. July wetland counts were similar in South Dakota (6%) and decreased in North Dakota
(-16) compared to July 2000. Although both states were wetter than long-term averages
(SD 30%, ND 52%), South Dakota decreased -13% and North Dakota was nearly
identical to the ten-year average. June rains benefitted habitat conditions more so in
North Dakota than in South Dakota. Generally, habitat conditions were good to excellent
through much of the crew area with limited areas of fair and/or poor conditions occurring
in the north west, the south east, and the north east. Upland and wetland basin cover was
lush throughout the region with negative impacts from farming observed only in fair and
poor areas. Those areas harboring good or excellent habitat should remain as such
through the brooding period.
2. The DBI in South Dakota decreased -22% compared to 2000 and is the seventh highest
index of record. The 2001 index is similar to the ten-year average and 99% above the
long-term average. In North Dakota, the 2001 DBI (173,800) decreased -20% since last
year but is 46% and 192% above the respective ten-year and long-term averages.,
Average brood sizes were similar to last year in both states. Statewide waterfowl
production in North and South Dakota is above average this year
3. Total LNI increased in South Dakota (132%) and decreased in North Dakota (-23%)
compared to 2000. The difference may be attributed to beneficial June rains in North
Dakota which caused more stability in wetland conditions and a more successful first
nesting effort. Both states were below the ten-year average (SD -18%, ND -45%) LNI.
Compared to the long-term average, South Dakota LNI was similar (10%) and North
Dakota was -56% below the LTA. Depending on precipitation during the next four to six
weeks, those late and second nesting birds in the good and excellent areas will have the
best chance for success
John W. Solberg and Sue Thomas
July 2001
Table 1. Long-term trend in waterfowl brood and late-nesting indices by species in South Dakota,
1959-2001 (index in thousands).a
_______________________________________________________________________________________________________________
Species 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
_______________________________________________________________________________________________________________
Broods
Duck brood index 130.2 115.4 89.7
Average brood sizeb 5.8 5.3 5.4
Coot brood index 20.7 5.4 8.1
Late-nesting indexc
Ducks
Dabblers
Mallard 13.6 6.0 18.6
Am. black duck 0.0 0.0 0.0
Gadwall 6.9 2.1 6.3
Am. wigeon 1.5 1.1 1.0
Green-winged teal 0.0 0.0 0.5
Blue-winged teal 4.8 1.0 3.9
N. shoveler 0.3 1.1 1.0
N. pintail 0.5 2.2 0.5
Subtotal 27.6 13.5 31.8
Divers
Redhead 1.1 0.2 1.8
Canvasback 0.0 0.0 0.2
Scaups 0.2 0.8 0.5
Ring-necked duck 0.0 0.0 0.2
Goldeneyes 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0
Ruddy duck 0.9 0.9 1.9
Subtotal 2.2 1.9 4.6
Miscellaneous
Oldsquaw 0.0 0.0 0.0
Eiders 0.0 0.0 0.0
Scoters 0.0 0.0 0.0
Mergansers 0.0 0.3 0.0
Subtotal 0.0 0.3 0.0
Total ducks 29.8 15.7 36.4
______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 1 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in South Dakota,
1959-2001 (index in thousands).a
_______________________________________________________________________________________________________________
Species 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
_______________________________________________________________________________________________________________
Broods
Duck brood index 25.7 18.9 27.5 14.3 36.4 110.9 68.5 114.4 118.8 119.5
Average brood sizeb 4.9 4.3 4.4 5.8 5.9 6.2 6.2 5.4 5.9 5.9
Coot brood index 2.6 1.9 1.5 5.0 4.7 15.6 12.9 15.3 12.6 10.6
Late-nesting indexc
Ducks
Dabblers
Mallard 11.1 38.0 30.2 21.7 25.4 5.2 30.8 17.9 8.0 7.6
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 6.6 23.7 16.8 11.3 17.4 4.3 24.1 9.5 4.9 4.7
Am. wigeon 1.8 3.0 2.7 1.8 2.2 1.5 4.8 3.5 1.5 3.0
Green-winged teal 0.0 0.3 0.0 0.3 0.2 0.0 0.7 0.5 0.0 0.0
Blue-winged teal 3.8 21.5 17.4 15.8 10.7 1.8 14.5 3.7 2.5 2.6
N. shoveler 0.4 2.2 2.4 1.5 3.5 0.3 0.8 1.0 0.5 1.0
N. pintail 4.5 1.9 6.2 1.3 4.4 1.8 4.9 2.5 1.0 1.8
Subtotal 28.3 90.5 75.7 53.7 63.8 14.9 80.6 38.6 18.4 20.7
Divers
Redhead 1.6 1.1 1.6 2.0 5.5 0.3 3.5 0.0 0.6 0.2
Canvasback 0.2 0.5 0.3 0.3 0.0 0.0 0.8 0.0 0.0 0.0
Scaups 0.2 0.2 0.2 0.3 1.6 0.0 1.2 0.2 0.5 0.2
Ring-necked duck 0.0 0.5 0.0 0.0 0.0 0.0 0.3 0.2 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ruddy duck 1.6 2.8 1.6 3.1 2.4 1.1 1.7 0.8 0.5 0.7
Subtotal 3.5 5.0 3.7 5.7 9.5 1.4 7.5 1.2 1.6 1.1
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.3 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.3 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 32.0 95.7 79.4 59.4 73.3 16.3 88.1 39.8 20.0 21.8
_______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 1 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in South Dakota,
1959-2001 (index in thousands).a
_______________________________________________________________________________________________________________
Species 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988
_______________________________________________________________________________________________________________
Broods
Duck brood index 28.7 16.3 6.5 41.4 41.3 58.6 23.4 65.0 56.8 20.8
Average brood sizeb 5.0 4.6 4.7 4.6 4.5 4.3 4.2 4.5 5.0 4.3
Coot brood index 1.2 3.3 0.8 3.5 5.2 8.6 2.7 8.3 8.0 1.1
Late-nesting indexc
Ducks
Dabblers
Mallard 6.7 3.9 4.5 10.7 14.4 21.6 8.8 13.4 6.3 4.4
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 2.0 1.0 2.5 5.1 12.6 14.1 2.8 6.8 3.5 2.5
Am. wigeon 1.6 0.2 1.2 2.1 2.2 5.4 2.7 1.9 1.9 0.3
Green-winged teal 0.3 0.5 0.0 0.0 0.0 0.2 0.3 0.5 0.5 0.5
Blue-winged teal 0.7 1.2 1.7 5.1 8.9 19.8 2.6 8.7 3.5 2.9
N. shoveler 0.3 0.3 0.2 1.1 0.7 4.9 0.2 1.6 1.2 1.4
N. pintail 0.7 0.5 2.0 4.0 4.2 10.2 1.2 5.0 2.3 1.5
Subtotal 12.2 7.6 11.9 28.0 42.9 76.1 18.4 38.0 19.2 13.6
Divers
Redhead 0.0 0.0 0.5 2.4 2.1 3.6 1.0 1.0 1.1 0.0
Canvasback 0.0 0.0 0.2 0.3 0.0 0.2 0.0 0.2 0.3 0.2
Scaups 0.0 0.0 0.0 0.3 0.8 0.0 0.2 0.3 0.7 0.0
Ring-necked duck 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.0 0.0
Ruddy duck 0.8 1.5 1.6 1.5 2.0 2.8 0.8 2.4 1.6 0.4
Subtotal 0.8 1.5 2.3 4.6 5.1 6.6 1.9 3.8 3.7 0.6
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 13.0 9.1 14.2 32.7 48.0 82.8 20.3 41.8 22.9 14.2
________________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 1 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in South Dakota,
1959-2001 (index in thousands).a
_______________________________________________________________________________________________________________
Species 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978
_______________________________________________________________________________________________________________
Broods
Duck brood index 41.5 38.7 26.3 58.8 42.3 18.8 21.1 10.9 20.7 45.3
Average brood sizeb 5.5 5.7 5.5 5.4 4.4 4.8 5.0 4.8 4.7 5.0
Coot brood index 4.7 3.3 1.0 6.6 1.8 0.3 0.0 0.3 0.3 0.9
Late-nesting indexc
Ducks
Dabblers
Mallard 12.6 11.9 5.9 13.8 11.0 9.1 12.3 5.2 4.7 8.5
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 9.0 4.6 3.8 8.1 3.4 8.2 8.0 2.4 1.8 6.3
Am. wigeon 1.3 2.4 0.0 2.5 2.3 1.0 1.5 1.2 2.2 2.3
Green-winged teal 0.9 2.1 0.0 0.0 0.0 0.7 0.2 0.0 0.0 0.6
Blue-winged teal 6.8 3.3 3.7 7.6 4.1 5.0 7.5 0.6 2.8 4.1
N. shoveler 1.1 1.6 0.0 0.3 1.2 0.0 0.0 0.0 0.4 0.8
N. pintail 2.4 2.0 1.0 2.8 4.3 1.7 1.5 2.5 1.1 3.4
Subtotal 34.1 27.9 14.4 35.0 26.3 25.7 31.0 11.9 13.0 26.1
Divers
Redhead 1.0 0.8 0.0 0.8 0.0 0.2 0.5 0.0 0.0 2.9
Canvasback 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.5
Scaups 0.0 1.0 0.0 0.0 0.5 0.0 0.0 0.0 0.3 0.4
Ring-necked duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ruddy duck 1.4 2.2 0.9 3.4 2.0 1.3 2.7 0.0 0.2 1.8
Subtotal 2.4 3.9 0.9 4.2 2.5 1.5 3.1 0.3 0.4 5.5
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 1.7 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.0 0.4 0.0 1.7 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 36.5 32.2 15.3 40.9 28.8 27.2 34.1 12.2 13.4 31.6
_______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 1 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in South Dakota,
1959-2001 (index in thousands).a
_______________________________________________________________________________________________________________
Species 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968
_______________________________________________________________________________________________________________
Broods
Duck brood index 11.2 33.5 41.2 42.2 62.8 11.6 18.8 45.1 22.7 23.3
Average brood sizeb 4.4 5.2 5.2 5.1 5.0 6.4 4.5 7.2 4.6 4.9
Coot brood index 0.3 0.6 2.2 2.7 1.0 1.1 0.4 15.2 2.6 2.4
Late-nesting indexc
Ducks
Dabblers
Mallard 6.6 11.1 7.4 14.0 3.5 6.1 19.1 8.4 14.3 6.6
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 0.0 1.4 0.1 5.9 3.3 2.5 7.2 6.0 7.3 2.6
Am. wigeon 0.0 0.1 0.3 0.3 0.0 0.0 0.0 0.0 2.3 1.3
Green-winged teal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.0
Blue-winged teal 1.3 2.6 4.5 21.7 2.2 7.6 9.2 1.0 6.2 1.0
N. shoveler 0.0 0.0 0.0 0.9 0.0 0.4 0.0 2.2 0.8 0.3
N. pintail 0.3 2.4 1.9 4.5 0.9 0.0 0.0 0.6 0.5 0.0
Subtotal 8.2 17.6 14.1 47.3 9.9 16.7 35.5 18.1 31.6 11.8
Divers
Redhead 0.0 0.3 0.1 1.7 0.3 0.6 3.0 0.0 0.2 0.0
Canvasback 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.6 0.0
Scaups 0.0 0.4 0.5 0.9 0.0 0.0 0.0 0.1 0.3 0.0
Ring-necked duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ruddy duck 0.0 1.1 4.7 1.9 2.4 0.4 6.0 4.7 1.6 0.8
Subtotal 0.0 1.8 5.3 4.5 2.7 1.1 9.0 4.9 2.7 0.8
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 8.2 19.5 19.4 51.8 12.6 17.8 44.4 22.9 34.4 12.5
_______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepanices may exist in column totals.
Table 2. Status of waterfowl brood and late-nesting indices by stratum in South Dakota, comparing 2001 with
2000, the 1991-2000 previous 10-year mean, and the 1959-2000 long-term mean (index in thousands).a
___________________________________________________________________________________________________________________
Percent change from
Strata (2001) 2001 2000 10-year Long-term 10-year Long-term
Species 44 48 49 Total Total Mean Mean 2000 Mean Mean
___________________________________________________________________________________________________________________
Broods
Duck brood index 24.1 57.1 8.5 89.7 115.4 85.6 45.1 -22% 5% 99%
Average brood sizeb 5.2 5.5 5.3 5.4 5.3 5.7 5.1 2% -5% 6%
Coot brood index 0.0 7.2 0.9 8.1 5.4 10.4 4.7 50% -22% 72%
Late-nesting indexc
Ducks
Dabblers
Mallard 7.0 7.9 3.7 18.6 6.0 16.6 12.0 210% 12% 55%
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Gadwall 0.8 4.2 1.3 6.3 2.1 10.2 6.6 200% -38% -5%
Am. wigeon 0.8 0.2 0.0 1.0 1.1 2.4 1.6 -9% -58% -38%
Green-winged teal 0.3 0.2 0.0 0.5 0.0 0.2 0.2 + 150% 150%
Blue-winged teal 1.6 1.9 0.4 3.9 1.0 7.5 6.1 290% -48% -36%
N. shoveler 0.8 0.2 0.0 1.0 1.1 1.2 0.9 -9% -17% 11%
N. pintail 0.0 0.5 0.0 0.5 2.2 2.7 2.3 -77% -81% -78%
Subtotal 11.3 15.1 5.4 31.8 13.5 40.8 29.8 136% -22% 7%
Divers
Redhead 0.0 1.4 0.4 1.8 0.2 1.5 1.0 800% 20% 80%
Canvasback 0.0 0.2 0.0 0.2 0.0 0.1 0.1 + 100% 100%
Scaups 0.3 0.2 0.0 0.5 0.8 0.5 0.3 -38% NC 67%
Ring-necked duck 0.0 0.2 0.0 0.2 0.0 0.1 0.0 + 100% +
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Ruddy duck 0.0 1.2 0.7 1.9 0.9 1.4 1.7 111% 36% 12%
Subtotal 0.3 3.2 1.1 4.6 1.9 3.6 3.2 142% 28% 44%
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Mergansers 0.0 0.0 0.0 0.0 0.3 0.0 0.1 - NC -
Subtotal 0.0 0.0 0.0 0.0 0.3 0.0 0.1 - NC -
Total ducks 11.6 18.3 6.5 36.4 15.7 44.4 33.0 132% -18% 10%
___________________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 3. Long-term trend in July pond indices by stratum in South Dakota, comparing 2001 with 2000, the
1991-2000 previous 10-year mean, the 1970-2000 long-term mean, and comparison of May with July
ponds in 2001 (estimates in thousands).a
________________________________________________________________________________________________________________
Strata
Year 44 48 49 Total
________________________________________________________________________________________________________________
1970 77.6 98.3 52.6 228.5
1971 115.1 117.7 70.5 303.3
1972 145.6 129.0 59.4 334.0
1973 119.3 76.0 54.8 250.2
1974 62.7 61.0 38.1 161.9
1975 105.4 80.7 39.4 225.5
1976 95.3 64.0 43.5 202.8
1977 93.8 43.2 25.5 162.6
1978 99.3 100.5 43.9 243.8
1979 114.6 61.4 37.4 213.3
1980 52.3 33.3 18.1 103.7
1981 75.8 37.5 31.7 145.0
1982 122.3 88.2 55.7 266.3
1983 74.6 134.3 125.9 334.7
1984 102.9 341.7 184.8 629.4
1985 120.1 93.2 71.8 285.1
1986 139.0 175.8 99.1 413.9
1987 133.7 102.1 60.2 296.0
1988 92.0 59.3 46.5 197.8
1989 119.6 74.2 46.3 240.0
1990 117.5 81.2 52.6 251.3
1991 113.2 130.8 64.4 308.4
1992 93.8 128.8 72.0 294.6
1993 406.4b 224.3 129.4 760.1
1994 143.8 194.7 94.1 432.6
1995 186.0 252.0 105.0 543.0
1996 112.5 223.9 100.2 436.6
1997 109.2 263.4 114.2 486.8
1998 170.4 248.5 110.0 528.9
1999 246.4 394.6 250.7 891.7
Table 3 (cont). Long-term trend in July pond indices by stratum in South Dakota, comparing 2001 with 2000, the
1991-2000 previous 10-year mean, the 1970-2000 long-term mean, and comparison of May with July
ponds in 2001 (estimates in thousands).a
________________________________________________________________________________________________________________
Strata
Year 44 48 49 Total
________________________________________________________________________________________________________________
2000 160.7 182.5 78.5 421.7
2001 146.8 197.0 101.5 445.3
2002
2003
2004
2005
2006
2007
2008
2009
10-year mean 174.2 224.4 111.9 510.4
Long-term mean 126.5 138.6 76.7 341.7
Percent Change
2001 from 2000 -9% 8% 29% 6%
2001 from 10-year mean -16% -12% -9% -13%
2001 from long-term mean 16% 42% 32% 30%
May ponds 2001 (adjusted) 105.3 562.9 320.9 989.1
Percent change
May to July 2001 39% -65% -68% -55%
(adjusted) (unadjusted)
aJuly ponds unadjusted for visibility bias.
bDue to an abnormally high visibility rate in May, 1993 July ponds for stratum 44 were calculated by applying %
change from May to July raw data, to adjusted May ponds.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 4. Survey design for South Dakota, July 2001.
_______________________________________________________________________________________________________
Stratum
44 48 49 Total
_______________________________________________________________________________________________________
Survey design
Square miles in stratum 28,930 24,587 15,830 67,716
Square miles in sample - water 216 315 171 702
Square miles in sample - ducks 108 157.5 85.5 351.0
Linear miles in sample 864 1,260 684 2,808
Number of transects in sample 5 9 11 25
Number of segments in sample 48 70 38 156
Expansion factor - water 133.9370 78.0539 92.5731 -
Expansion factor - ducks 267.8740 156.1079 185.1462 -
Current year coverage
Square miles in sample - water 207 279 171 657
Square miles in sample - ducks 103.5 139.5 85.5 328.5
Linear miles in sample 828 1,116 684 2,628
Number of transects in sample 5 9 11 25
Number of segments in sample 48 62 38 148
Expansion factor - water 133.9370 88.1255 92.5731 -
Expansion factor - ducks 267.8740 176.2510 185.1462 -
_______________________________________________________________________________________________________
Table 5. Long-term trend in waterfowl brood and late-nesting indices by species in North Dakota,
1958-2001 (index in thousands).a
_____________________________________________________________________________________________________________
Species 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
_____________________________________________________________________________________________________________
Broods
Duck brood index 196.7 189.4 217.6 173.8
Average brood sizeb 6.2 6.6 5.3 5.0
Coot brood index 78.6 82.5 66.7 33.2
Late-nesting indexc
Ducks
Dabblers
Mallard 3.3 5.1 3.9 4.7
Am. black duck 0.0 0.0 0.0 0.0
Gadwall 3.1 1.5 2.6 1.2
Am. wigeon 0.9 0.5 0.0 0.8
Green-winged teal 0.0 0.0 0.1 0.0
Blue-winged teal 2.4 1.1 2.6 1.6
N. shoveler 0.8 0.2 0.5 0.5
N. pintail 0.0 0.5 1.0 0.0
Subtotal 10.5 8.9 10.7 8.8
Divers
Redhead 0.7 0.4 0.5 0.3
Canvasback 0.0 0.0 0.0 0.0
Scaups 0.1 0.0 0.9 0.0
Ring-necked duck 0.1 0.0 0.0 0.2
Goldeneyes 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0
Ruddy duck 4.7 2.6 2.8 2.2
Subtotal 5.6 3.0 4.2 2.7
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0
Total ducks 16.1 11.9 14.9 11.5
______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 5 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in North Dakota,
1958-2001 (index in thousands).a
_____________________________________________________________________________________________________________
Species 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
_____________________________________________________________________________________________________________
Broods
Duck brood index 46.9 40.9 14.3 23.5 17.5 29.3 85.3 107.3 155.9 171.1
Average brood sizeb 4.8 4.8 4.5 5.3 5.7 6.1 5.7 6.1 6.0 5.7
Coot brood index 5.7 3.7 1.3 1.1 4.3 5.1 25.2 52.8 62.9 87.7
Late-nesting indexc
Ducks
Dabblers
Mallard 3.8 11.7 11.8 9.0 7.8 10.7 3.1 5.5 7.5 2.3
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 3.1 3.4 5.7 3.4 3.6 13.0 0.9 6.5 7.1 2.6
Am. wigeon 1.0 1.5 0.7 0.9 1.3 1.5 0.9 0.7 1.4 0.4
Green-winged teal 0.1 0.0 0.0 0.0 0.2 0.1 0.2 0.1 0.1 0.2
Blue-winged teal 2.8 3.3 6.2 5.0 4.0 4.1 0.5 4.5 2.4 2.3
N. shoveler 0.5 0.3 0.6 0.8 0.1 0.4 0.0 0.0 0.0 0.7
N. pintail 2.2 3.9 0.8 1.5 1.1 0.8 0.7 0.3 1.7 0.0
Subtotal 13.5 24.1 25.9 20.7 18.1 30.6 6.3 17.6 20.2 8.5
Divers
Redhead 0.8 1.2 1.3 0.4 1.4 4.0 0.9 1.8 1.0 0.7
Canvasback 0.0 0.8 1.2 0.3 0.0 0.3 0.0 0.1 0.0 0.0
Scaups 0.3 0.3 0.5 0.0 0.2 0.0 0.2 0.1 0.3 0.0
Ring-necked duck 0.0 0.2 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.1
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0
Ruddy duck 0.7 3.0 1.0 1.6 3.5 4.8 2.9 7.8 9.6 1.2
Subtotal 1.8 5.5 4.1 2.4 5.1 9.3 4.2 9.8 10.9 2.0
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0 0.0
Total ducks 15.2 29.6 29.9 23.1 23.2 40.1 10.5 27.4 31.1 10.5
______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 5 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in North Dakota,
1958-2001 (index in thousands).a
__________________________________________________________________________________________________________________
Species 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987
__________________________________________________________________________________________________________________
Broods
Duck brood index 37.6 30.7 37.8 25.5 72.7 52.2 84.3 46.6 62.0 91.9
Average brood sizeb 5.5 5.1 4.8 4.8 5.0 4.7 4.3 4.6 4.5 4.8
Coot brood index 1.2 3.4 3.6 3.5 30.6 12.1 11.9 11.9 14.4 28.8
Late-nesting indexc
Ducks
Dabblers
Mallard 5.2 2.7 2.3 3.8 13.1 9.3 13.9 5.3 4.8 4.7
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 1.9 2.0 0.3 1.6 6.7 14.2 10.4 2.7 1.3 4.2
Am. wigeon 0.5 0.4 0.1 1.0 3.0 2.1 1.5 1.2 1.1 0.9
Green-winged teal 0.0 0.0 0.2 0.2 0.2 0.9 0.1 0.1 0.3 0.3
Blue-winged teal 1.4 1.0 0.0 1.2 7.1 8.2 6.2 2.3 2.7 4.1
N. shoveler 0.0 0.5 0.0 0.2 1.7 1.0 1.1 0.7 0.6 1.1
N. pintail 3.5 1.9 0.2 1.1 1.6 6.3 2.8 1.5 1.2 3.0
Subtotal 12.5 8.4 3.1 9.1 33.4 42.0 36.0 13.8 12.0 18.2
Divers
Redhead 2.7 0.7 0.0 0.0 3.4 2.4 1.6 0.9 0.3 2.3
Canvasback 0.4 0.1 0.2 0.3 0.7 0.2 1.0 0.1 0.2 0.2
Scaups 0.3 0.3 0.0 0.0 0.9 3.5 4.3 1.1 0.4 1.8
Ring-necked duck 0.0 0.0 0.0 0.0 0.0 0.4 0.0 0.0 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ruddy duck 2.3 1.3 0.7 1.2 13.2 9.6 9.0 3.2 2.5 4.5
Subtotal 5.8 2.4 0.8 1.5 18.2 16.2 16.1 5.3 3.4 8.8
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 18.3 10.8 3.9 10.6 51.5 58.1 52.1 19.2 15.4 27.0
__________________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 5 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in North Dakota,
1958-2001 (index in thousands).a
__________________________________________________________________________________________________________________
Species 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977
__________________________________________________________________________________________________________________
Broods
Duck brood index 27.3 50.0 57.6 39.0 51.9 36.9 34.1 41.1 28.3 29.9
Average brood sizeb 5.5 6.2 6.5 5.6 5.5 5.2 5.8 5.7 5.7 4.5
Coot brood index 5.2 14.2 19.5 15.0 16.0 8.1 12.6 6.4 5.4 1.2
Late-nesting indexc
Ducks
Dabblers
Mallard 7.9 9.4 9.7 9.0 9.6 7.7 8.5 33.1 8.6 3.6
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 4.9 9.6 5.9 6.3 10.7 2.0 15.1 31.4 3.2 2.0
Am. wigeon 0.6 0.9 0.0 0.3 1.0 1.6 0.4 1.1 0.6 0.4
Green-winged teal 0.0 1.0 2.6 0.5 0.2 0.2 0.3 0.0 0.4 0.2
Blue-winged teal 0.4 11.7 2.4 4.8 7.7 2.9 11.0 29.8 1.4 1.7
N. shoveler 0.0 0.7 0.1 0.0 0.2 0.0 0.0 0.8 1.0 0.0
N. pintail 0.0 3.2 2.0 0.6 1.5 0.6 0.4 3.1 3.1 1.5
Subtotal 13.8 36.6 22.7 21.5 30.8 15.0 35.7 99.3 18.3 9.3
Divers
Redhead 0.2 1.4 1.6 0.1 0.7 0.5 0.6 3.4 0.3 0.3
Canvasback 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.2 0.0 0.2
Scaups 0.0 0.6 0.3 0.3 0.3 0.2 0.9 0.3 0.0 0.0
Ring-necked duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ruddy duck 3.1 4.7 5.0 1.4 5.6 1.6 4.8 8.4 4.0 0.5
Subtotal 3.3 6.7 7.0 1.9 6.7 2.9 6.2 12.3 4.4 1.0
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 17.1 43.3 29.8 23.3 37.5 17.9 41.9 111.6 22.7 10.3
__________________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 5 (cont). Long-term trend in waterfowl brood and late-nesting indices by species in North Dakota,
1958-2001 (index in thousands).a
________________________________________________________________________________________________________________
Species 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967
________________________________________________________________________________________________________________
Broods
Duck brood index 68.7 13.5 42.5 26.7 24.3 31.6 15.6 15.9 41.6 49.5
Average brood sizeb 5.6 4.9 5.4 4.1 4.7 5.0 5.6 6.1 6.6 5.4
Coot brood index 13.3 1.3 4.8 1.1 1.4 1.4 3.1 4.0 21.7 14.9
Late-nesting indexc
Ducks
Dabblers
Mallard 4.5 4.2 9.4 3.5 19.9 6.7 5.5 6.0 9.9 17.4
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Gadwall 1.7 0.6 2.7 2.3 6.2 0.6 2.8 6.5 3.2 14.0
Am. wigeon 1.1 0.0 0.0 0.0 0.0 0.8 0.0 0.3 0.0 0.9
Green-winged teal 0.0 0.0 0.0 0.2 0.0 0.2 0.0 0.0 0.2 0.5
Blue-winged teal 2.1 0.6 4.0 1.5 13.9 3.8 5.5 3.6 3.3 10.5
N. shoveler 0.2 0.0 0.2 0.0 0.9 0.0 1.0 0.0 1.3 0.2
N. pintail 0.0 1.1 0.6 2.1 4.1 0.0 0.0 0.0 1.2 1.6
Subtotal 9.6 6.4 16.9 9.7 45.0 12.1 14.7 16.3 19.0 45.0
Divers
Redhead 0.0 0.0 1.3 0.2 3.8 0.2 0.0 0.3 0.7 0.8
Canvasback 0.3 0.6 0.3 0.2 0.0 0.0 0.0 0.0 0.0 0.0
Scaups 0.0 0.3 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.1
Ring-necked duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ruddy duck 0.0 1.9 3.8 1.7 4.3 2.4 0.6 1.5 5.7 4.4
Subtotal 0.3 2.8 5.8 2.2 8.1 2.6 0.6 1.8 6.4 5.4
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mergansers 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Subtotal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Total ducks 9.9 9.3 22.8 11.8 53.1 14.7 15.3 18.1 25.4 50.4
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aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 6. Status of waterfowl brood and late-nesting indices by stratum in North Dakota, comparing 2001 with
2000, the 1991-2000 previous 10-year mean, and the 1958-2000 long-term mean (index in thousands).a
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Percent change from
Strata (2001) 2001 2000 10-year Long-term 10-year Long-term
Species 43 45 46 47 Total Total Mean Mean 2000 Mean Mean
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Broods
Duck brood index 20.6 92.2 57.5 3.5 173.8 217.6 119.4 59.6 -20% 46% 192%
Average brood sizeb 4.8 5.1 5.0 4.2 5.0 5.3 5.9 5.4 -6% -15% -7%
Coot brood index 1.1 24.6 7.2 0.3 33.2 66.7 46.7 17.9 -50% -29% 85%
Late-nesting indexc
Ducks
Dabblers
Mallard 3.6 0.5 0.6 0.0 4.7 3.9 5.8 8.0 21% -19% -41%
Am. black duck 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Gadwall 0.7 0.0 0.5 0.0 1.2 2.6 4.4 5.4 -54% -73% -78%
Am. wigeon 0.7 0.0 0.1 0.0 0.8 0.0 0.9 0.8 + -11 NC
Green-winged teal 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.2 - - -
Blue-winged teal 0.9 0.5 0.2 0.0 1.6 2.6 2.9 4.6 -38% -45% -65%
N. shoveler 0.5 0.0 0.0 0.0 0.5 0.5 0.4 0.4 NC 25% 25%
N. pintail 0.0 0.0 0.0 0.0 0.0 1.0 0.8 1.5 - - -
Subtotal 6.4 1.0 1.4 0.0 8.8 10.7 15.2 21.0 -18% -42% -58%
Divers
Redhead 0.0 0.0 0.3 0.0 0.3 0.5 1.2 1.1 -40% -75% -73%
Canvasback 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.2 NC - -
Scaups 0.0 0.0 0.0 0.0 0.0 0.9 0.2 0.4 - - -
Ring-necked duck 0.0 0.0 0.2 0.0 0.2 0.0 0.0 0.0 + + +
Goldeneyes 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Bufflehead 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Ruddy duck 0.9 0.9 0.4 0.0 2.2 2.8 4.2 3.7 -21% -48% -41%
Subtotal 0.9 0.9 0.9 0.0 2.7 4.2 5.7 5.5 -36% -53% -51%
Miscellaneous
Oldsquaw 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Eiders 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Scoters 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Mergansers 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Subtotal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 NC NC NC
Total ducks 7.3 1.9 2.3 0.0 11.5 14.9 20.9 26.4 -23% -45% -56%
_______________________________________________________________________________________________________________
aUnadjusted for visibility bias.
bFrom complete Class II and III broods observed.
cAs indicated by observed adult pairs and singles.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 7. Long-term trend in July pond indices by stratum in North Dakota, comparing 2001 with 2000, the 1991-
2000 previous 10-year mean, the 1970-2000 long-term mean, and comparison of May with July ponds in
2001 (estimates in thousands).a
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Strata
Year 43 45 46 47 Total
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1970 46.1 286.1 80.4 23.2 435.7
1971 104.4 230.8 77.9 9.7 422.9
1972 71.9 191.1 57.5 10.4 330.9
1973 87.3 130.7 24.5 7.3 249.7
1974 42.0 194.7 44.5 15.6 296.8
1975 73.9 213.2 155.6 25.0 467.7
1976 74.0 215.2 63.4 8.7 361.3
1977 68.7 71.2 32.4 2.8 175.0
1978 59.4 104.3 64.4 2.1 230.2
1979 79.1 156.7 66.0 15.6 317.5
1980 38.7 51.1 30.3 2.4 122.5
1981 55.2 95.9 35.0 8.7 194.7
1982 97.6 175.6 73.8 10.8 357.9
1983 50.4 281.3 140.4 21.6 493.6
1984 75.0 265.0 143.6 15.6 499.3
1985 94.9 132.1 51.4 9.7 288.1
1986 101.9 182.8 94.1 18.8 397.6
1987 88.6 149.9 93.4 5.2 337.2
1988 63.3 79.2 34.1 4.2 180.8
1989 105.1 63.3 39.3 5.6 213.3
1990 99.5 75.3 36.2 5.6 216.5
1991 99.2 60.4 53.4 5.6 218.6
1992 76.2 70.0 44.6 9.7 200.5
1993 229.8b 312.0 174.4 18.4 734.6
1994 97.6 211.8 156.4 19.1 484.9
1995 146.2 343.9 260.3 27.5 777.9
1996 73.2 330.1 206.9 15.6 625.8
1997 73.5 344.2 238.9 26.1 682.7
1998 78.0 274.4 218.3 25.0 595.7
1999 137.4 811.9 338.7 27.1 1315.1
Table 7 (cont). Long-term trend in July pond indices by stratum in North Dakota, comparing 2001 with 2000, the 1991-
2000 previous 10-year mean, the 1970-2000 long-term mean, and comparison of May with July ponds in
2001 (estimates in thousands).a
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Strata
Year 43 45 46 47 Total
________________________________________________________________________________________________________________
2000 99.8 416.8 219.9 19.8 756.3
2001 131.1 334.2 160.1 12.5 637.9
2002
2003
2004
2005
2006
2007
2008
2009
10-year mean 111.1 317.6 191.2 19.4 639.2
Long-term mean 86.7 210.4 108.1 13.6 418.8
Percent Change
2001 from 2000 31% -20% -27% -37% -16%
2001 from 10-year mean 18% 5% -16% -36% NC
2001 from long-term mean 51% 59% 48% -8% 52%
May ponds 2001 (adjusted) 86.2 414.9 222.1 26.9 750.2
Percent change
May to July 2001
(adjusted)(unadjusted) 52% -19% -28% -54% -15%
aJuly ponds unadjusted for visibility bias.
bDue to an abnormally high visibility rate in May, 1993 July ponds for stratum 43 were calculated by applying %
change from May to July raw data, to adjusted May ponds.
Resulting from rounding techniques, slight discrepancies may exist in column totals.
Table 8. Survey design for North Dakota, July 2001.
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Stratum
43 45 46 47 Total
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Survey design
Square miles in stratum 19,835 26,625 14,238 7,821 68,519
Square miles in sample - water 175.5 310.5 270 45 801
Square miles in sample - ducks 87.75 155.25 135.0 22.5 400.5
Linear miles in sample 702 1,242 1,080 180 3,204
Number of transects in sample 5 7 8 6 26
Number of segments in sample 39 69 60 10 178
Expansion factor - water 113.0200 85.7488 52.7334 173.8000 -
Expansion factor - ducks 226.0399 171.4976 105.4667 347.6000 -
Current year coverage
Square miles in sample - water 175.5 297.0 270 45 787.5
Square miles in sample - ducks 87.75 148.5 135.0 22.5 393.75
Linear miles in sample 702 1,188 1,080 180 3,150
Number of transects in sample 5 7 8 6 26
Number of segments in sample 39 66 60 10 175
Expansion factor - water 113.0200 89.6465 52.7334 173.8000 -
Expansion factor - ducks 226.0399 179.2930 105.4667 347.6000 -
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