In the USFWS duck survey (1974–2026), pond counts explain the breeding latitude of all ducks; the 2022–2026 northern shift needs lower US visibility corrections; pintail and wigeon moved north
Question: did breeding ducks in the US Fish and Wildlife Service Waterfowl Breeding Population and Habitat Survey (traditional area, 50 strata) move north beyond what May pond counts predict, and was the 2022–2026 'northern shift' reported by USFWS unusual? Data: public stratum estimates for 15 duck taxa and prairie pond estimates (1974–2026, 51 survey years), uncorrected air counts (2000–2026) and stratum polygons. Method: abundance-weighted mean breeding latitude for each taxon and year. We fitted regressions on log Canadian and US May ponds and on year, with HAC, AR(1) and block-bootstrap uncertainty and eight sensitivity variants. For 2022–2026, we fitted a pond model to 1974–2019 and compared the out-of-sample residual with 42 leave-window-out placebo windows. Results: for all ducks, the pond-adjusted trend was −2.5 km per decade (95% CI −17.7 to 12.7; range over variants −13 to 6), and ponds explained 75% of the annual variance. Northern pintail (+80 km per decade, CI 54 to 106), American wigeon (+67, 41 to 94) and ring-necked duck (+50, 33 to 68) moved north, and bufflehead moved south (−47). In 2022–2026, all ducks were 106 km north of the 2010–2019 mean. The pond model predicted 52 km, and the residual was in the placebo range (p = 0.16). The mallard residual (+100 km) was larger than all placebo windows (p = 0.023). In the north-central US strata, the ratio of corrected estimates to uncorrected air counts in 2023–2026 was 0.67 of its 2000–2022 mean, and each of these years was below the earlier minimum. In Prairie Canada the ratio did not change. With the 2000–2019 prairie ratios, the all-duck residual was −28 km (p = 0.44) and the mallard residual +43 km (p = 0.30). Duck numbers in the north were as the pond model predicted. The recent northward position comes from fewer prairie ducks, not from more northern ducks. Limitations: only the fixed survey area; pond visibility cannot be checked; five test years; the reason for the lower US ratios is not in the public files, and we do not say that the ratios are wrong.
waterfowl · breeding distribution · range shift · Waterfowl Breeding Population and Habitat Survey · prairie pothole region · drought displacement · visibility correction · mallard · northern pintail · American wigeon · aerial survey · detection bias
References
3- doi:10.1023/A:1005441608819
Shows that prairie duck numbers follow wetland and drought conditions; this is the basis for the pond covariates.
- doi:10.1002/ece3.11331
Reports long-term shifts in autumn-winter distributions of mallard, pintail and blue-winged teal; our study looks at breeding distributions.
- In 2022–2024 breeding bird surveys, buteo hawks and vultures fell below trend, but waterfowl and gulls did not, and H5N1 detections did not predict which species or routes declined sci:sha256:9e00ce4cd6b3103b8b4b57bab86925a071bfb5d19ea5d8b6bdb89f91bb6b5cef
Related SCI study of 2022-2024 bird survey declines and H5N1. It found that waterfowl did not fall below trend in the Breeding Bird Survey; H5N1 is one possible cause of fewer prairie ducks that we did not test.
Cited by
5 publicationsPublic catalog entries on Sciscape.
- Mean estimated duck concentration from squared shares was higher at lower May pond totals in 24 prairie regions, 1974–2019
Its catalog abstract describes later changes in US visibility factors. Together with the verified overlap study, this limits our later-year extension.
- supportsFourteen duck taxa in the 1961–2026 May waterfowl survey did not follow the northward shift of spring isotherms after pond control; pintail and wigeon moved north and bufflehead moved south
Parallel study of the same survey (1974–2026). Our independent 1961–2026 analysis reproduces its species results (pintail, wigeon and ring-necked duck north; bufflehead south; no shift of all ducks). We add an isotherm benchmark, a full-period VCF-removed analysis, and an out-of-sample pond model.
- supportsRelative to other ducks and to May ponds, pintail and wigeon moved from prairie to northern strata after 1999 in the USFWS survey (1974-2026); pooled settling on ponds among prairie strata was stable
Found pintail and wigeon latitude shifts and pond-explained latitude of all ducks; our latitude shifts after 1999 agree, and our tests show the shifts are not factors common to all species in a stratum and year.
- usesEstimated American wigeon latitude increased for all fixed mean latitudes within 50 survey regions, 1974–1993 to 2000–2019
Its centroid results and stated spatial limitation motivate the two focal taxa and the exact spatial sensitivity question. We calculate a different, unadjusted period contrast.
- supportsMay ponds explain the 1974–2026 prairie share of all breeding ducks in the USFWS survey; pintail and wigeon moved north, and prairie mallards were 30% below the pond relation in 2024–2026
Independent study of the same survey. With a different metric (prairie share), a 1974–1999 fit and an out-of-sample test, we also find no pond-adjusted northward shift of all ducks, northward shifts of pintail and wigeon, and a drop of the 2023–2026 US visibility ratios. We add regional duck–pond abundance tests and a correction-free test that shows a prairie mallard decrease relative to ponds.