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

Gadwall Population Trend in Washington

All statesWaterfowl

Gadwall in Washington has increased: up 40% on the route-weighted index since 1975.

+40%Since 1975TrendPercent 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 →
30Routes 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 WashingtonNotable 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 Washington. See the full index history below.

Gadwall Population Forecast in Washington

If the recent trend holds, Gadwall in Washington is projected to rise about 879% by 2029 — from 0.05 in 2024 to a central estimate of 0.52 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±403.4%, with 80% of held-out values landing inside the 95% band.

+879%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 →
0.52Projected 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 →
0.00–1.195% 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 →
±403.4%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 Washington is projected to rise about 879% by 2029 — from 0.05 in 2024 to a central estimate of 0.52 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±403.4%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20250.500.001.1
20260.510.001.1
20270.510.001.1
20280.510.001.1
20290.520.001.1

Gadwall Survey Routes in Washington

Routes recording Gadwall in Washington.
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 →
Brewster3520181983
Columbia Nwr3420211992
Othello1319911984
Rimrock520152015
Wilbur520221984
Mesa419971997
Turnbull Nwr320181993
Moses Lake320151973
Scootney Reservoir320092009
Keystone320241994
Port Angeles220102006
Chewelah219911991
Deception219971996
Cusick220231996
Nighthawk220192011
Moses Coulee220231996
Odessa220222001
Warm Beach120021999
Hanford Site119891989
L Pend O Nwr120222014
Harrington119841981
Reardan120181968
Horn Rapids120162012
Malden120042001
Potholes120191996

Gadwall Population Trend in Other States

alaskaarizonacaliforniacoloradodelawareidahoillinoisiowakansasmassachusettsmichiganminnesotamissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-dakotaoklahomaoregonpennsylvaniarhode-islandsouth-dakotatexasutahvermontwisconsinwyoming

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