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

Gadwall Population Trend in Montana

All statesWaterfowl

Gadwall in Montana has held roughly steady: down 7% on the route-weighted index since 1972.

-7%Since 1972TrendPercent 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 →
69Routes 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 →
53YearsYears 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 MontanaNotable 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 Montana. See the full index history below.

Gadwall Population Forecast in Montana

If the recent trend holds, Gadwall in Montana is projected to rise about 57% by 2029 — from 0.89 in 2024 to a central estimate of 1.4 (95% range 0.00–3.2). A 5-year backtest shows a typical error of ±39.6%, with 100% of held-out values landing inside the 95% band.

+57%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 →
1.4Projected 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 →
0.00–3.295% 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 →
±39.6%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 Montana is projected to rise about 57% by 2029 — from 0.89 in 2024 to a central estimate of 1.4 (95% range 0.00–3.2). A 5-year backtest shows a typical error of ±39.6%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20251.40.003.2
20261.40.003.2
20271.40.003.2
20281.40.003.2
20291.40.003.2

Gadwall Survey Routes in Montana

Routes recording Gadwall in Montana.
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 →
Westby1620242015
Dinosaurs H.M.1520212018
Sunburst1220071970
Ester Lake920242015
Brandenberg820072007
Malta620241975
Chinook620242015
Sun River620232017
Roundup620242018
Pablo Res.620231995
Great Falls520231972
Locate520221982
Red Rock520221973
Virgelle420241979
Two Dot420241987
Beaverhead420231974
Gildford420242015
Glentana420242015
Winnett420232018
Cleveland320141988
Oswego320231978
Augusta320221978
Leroy320181980
Willow Creek 2320212003
Wolf Creek320192018

Gadwall Population Trend in Other States

alaskaarizonacaliforniacoloradodelawareidahoillinoisiowakansasmassachusettsmichiganminnesotamissourinebraskanevadanew-jerseynew-mexiconew-yorknorth-dakotaoklahomaoregonpennsylvaniarhode-islandsouth-dakotatexasutahvermontwashingtonwisconsinwyoming

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