BirdAnalyst
Species · Nebraska · BBS 2025 Release · 1966–2024

Gadwall Population Trend in Nebraska

All statesWaterfowl

Gadwall in Nebraska has declined: down 38% on the route-weighted index since 1969.

-38%Since 1969TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
15Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
47YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Gadwall Trends in NebraskaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Gadwall in Nebraska. See the full index history below.

Gadwall Population Forecast in Nebraska

If the recent trend holds, Gadwall in Nebraska is projected to stay roughly flat through 2029, near 0.16 (95% range 0.00–0.48). A 5-year backtest shows a typical error of ±412%, with 100% of held-out values landing inside the 95% band.

-7%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.16Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.4895% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±412%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Gadwall in Nebraska is projected to stay roughly flat through 2029, near 0.16 (95% range 0.00–0.48). A 5-year backtest shows a typical error of ±412%, with 100% of held-out values landing inside the 95% band.19672029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20250.160.000.49
20260.160.000.48
20270.160.000.48
20280.160.000.48
20290.160.000.48

Gadwall Survey Routes in Nebraska

Routes recording Gadwall in Nebraska.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Piester Lake620161967
Arthur420242022
Crescent Lk420161980
Kennedy420241995
Swan Lake320211983
Agate 2220092009
Oglala Nat. Grass.220151999
Ringgold220052003
Murray Lake220101997
Pine Ridge220002000
Nenzel220212021
Wheeler Co220221982
Table120172007
Gordon120131976
Brownlee120181992

Gadwall Population Trend in Other States

alaskaarizonacaliforniacoloradodelawareidahoillinoisiowakansasmassachusettsmichiganminnesotamissourimontananevadanew-jerseynew-mexiconew-yorknorth-dakotaoklahomaoregonpennsylvaniarhode-islandsouth-dakotatexasutahvermontwashingtonwisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.