BirdAnalyst
Species · South Dakota · BBS 2026 Release · 1966–2025

Gadwall Population Trend in South Dakota

All statesWaterfowl

Gadwall in South Dakota has declined: down 33% on the route-weighted index since 1969.

-33%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 →
49Routes 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 →
58YearsYears 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 South DakotaNotable 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 South Dakota. See the full index history below.

Gadwall Population Forecast in South Dakota

If the recent trend holds, Gadwall in South Dakota is projected to rise about 583% by 2030 — from 0.46 in 2025 to a central estimate of 3.2 (95% range 0.00–6.7). A 5-year backtest shows a typical error of ±188%, with 100% of held-out values landing inside the 95% band.

+583%Change by 2030TrendPercent 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 →
3.2Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–6.795% 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 →
±188%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 South Dakota is projected to rise about 583% by 2030 — from 0.46 in 2025 to a central estimate of 3.2 (95% range 0.00–6.7). A 5-year backtest shows a typical error of ±188%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20263.20.006.7
20273.20.006.7
20283.20.006.7
20293.20.006.7
20303.20.006.7

Gadwall Survey Routes in South Dakota

Routes recording Gadwall in South Dakota.
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 →
Raymond3120211967
White Lake2120111967
Long Lake1920191967
Gorman1920101979
Gettysburg1120231993
Laplant1120111973
Cottonwood1120241992
Conde1019841967
White River1020121994
Chamberlain820111968
Isabel720152011
Ardmore720191977
Lacreek720231991
Lane 2720142002
Crow Creek520231967
Britton520231969
Lodgepole520251995
Volga420241967
Harding420171968
French Creek420041995
Lennox320151969
Ottumwa320251967
Howard220251979
Winner220101977
Broadland220141968

Gadwall Population Trend in Other States

alaskaarizonacaliforniacoloradodelawareidahoillinoisindianaiowakansasmassachusettsmichiganminnesotamissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-dakotaoklahomaoregonpennsylvaniarhode-islandtexasutahvermontwashingtonwisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.