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

Willow Flycatcher Population Trend in Idaho

All statesAerial insectivores

Willow Flycatcher in Idaho has surged: up 118% on the route-weighted index since 1971.

+118%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 →
53Routes 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 Willow Flycatcher Trends in IdahoNotable 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 →

Willow Flycatcher has surged in Idaho: up 118% on the route-weighted index since 1971.

Willow Flycatcher Population Forecast in Idaho

If the recent trend holds, Willow Flycatcher in Idaho is projected to fall about 10% by 2030 — from 2.5 in 2025 to a central estimate of 2.3 (95% range 0.47–4.1). A 5-year backtest shows a typical error of ±27.9%, with 100% of held-out values landing inside the 95% band.

-10%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 →
2.3Projected 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 →
0.47–4.195% 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 →
±27.9%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, Willow Flycatcher in Idaho is projected to fall about 10% by 2030 — from 2.5 in 2025 to a central estimate of 2.3 (95% range 0.47–4.1). A 5-year backtest shows a typical error of ±27.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20262.30.484.1
20272.30.484.1
20282.30.474.1
20292.30.474.1
20302.30.474.1

Willow Flycatcher Survey Routes in Idaho

Routes recording Willow Flycatcher in Idaho.
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 →
Naples2920251973
Cabarton2720241985
Pierce1520071990
Almo1320251988
Joel1220241989
Cascade1119841971
Challis820251975
Nezperce Nf719991992
Gifford620171971
Cape Horn620251987
Grangeville519861986
Golden520161987
N Fork Cda R520191994
Alturas519861968
Coolin520251986
Sawtooth City 2420252015
Marble Creek420251988
Rochat Divde420251993
Mivoden320251977
Avery320251979
Nezperce320121992
Lolo Pass320191997
Baker320241974
Cobalt320241991
Deep Creek219851985

Willow Flycatcher Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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