BirdAnalyst
Species · Montana · BBS 2026 Release · 1966–2025

Willet Population Trend in Montana

All statesShorebirds

Willet in Montana has surged: up 510% on the route-weighted index since 1971.

+510%Since 1971TrendPercent 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 →
46Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Willet 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 →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Willet has surged in Montana: up 510% on the route-weighted index since 1971.

Willet Population Forecast in Montana

If the recent trend holds, Willet in Montana is projected to rise about 56% by 2030 — from 0.43 in 2025 to a central estimate of 0.68 (95% range 0.14–1.2). A 5-year backtest shows a typical error of ±24.1%, with 100% of held-out values landing inside the 95% band.

+56%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 →
0.68Projected 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 →
0.14–1.295% 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 →
±24.1%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, Willet in Montana is projected to rise about 56% by 2030 — from 0.43 in 2025 to a central estimate of 0.68 (95% range 0.14–1.2). A 5-year backtest shows a typical error of ±24.1%, with 100% of held-out values landing inside the 95% band.19692030
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 →
20260.660.121.2
20270.660.121.2
20280.670.131.2
20290.670.131.2
20300.680.141.2

Willet Survey Routes in Montana

Routes recording Willet 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 →
Westby1320252015
Highwood920171999
Cleveland420231985
Great Falls420231972
Chinook420252015
Ester Lake420252015
Harlem320211980
Glasgow320251970
Polson319941994
Lima319991999
Sunburst220051971
Malta220251975
Oswego220241978
Redstone220241969
Roy220231993
Flatwillow 2220182018
Ingomar220251988
Beaverhead220251973
Red Rock220081974
East Glacier Park220182018
Gildford220252015
Sun River220232016
Roundup220252016
Wheat Basin220232017
St. Mary 2220242010

Willet Population Trend in Other States

alabamacaliforniacoloradoconnecticutdelawarefloridaidaholouisianamainemarylandmassachusettsminnesotanebraskanevadanew-jerseynew-yorknorth-carolinanorth-dakotaoregonsouth-carolinasouth-dakotatexasutahvirginiawyoming

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