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

Willow Flycatcher Population Trend in Iowa

All statesAerial insectivores

Willow Flycatcher in Iowa has edged up: up 13% on the route-weighted index since 1969.

+13%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 →
34Routes 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 →
57YearsYears 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 IowaNotable 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 Willow Flycatcher in Iowa. See the full index history below.

Willow Flycatcher Population Forecast in Iowa

If the recent trend holds, Willow Flycatcher in Iowa is projected to fall about 15% by 2029 — from 0.77 in 2024 to a central estimate of 0.66 (95% range 0.26–1.1). A 5-year backtest shows a typical error of ±30.5%, with 100% of held-out values landing inside the 95% band.

-15%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 →
0.66Projected 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 →
0.26–1.195% 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 →
±30.5%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 Iowa is projected to fall about 15% by 2029 — from 0.77 in 2024 to a central estimate of 0.66 (95% range 0.26–1.1). A 5-year backtest shows a typical error of ±30.5%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.650.251.0
20260.650.251.0
20270.650.261.0
20280.650.261.0
20290.660.261.1

Willow Flycatcher Survey Routes in Iowa

Routes recording Willow Flycatcher in Iowa.
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 →
Davis Corner520241977
Exline320241980
Bedford320151991
Bryant320241967
Brooklyn320211974
Melrose220241976
West Liberty220231972
Williamsburg220231979
Red Rock220121993
Wales220162013
Prairieburg220191967
Hudson219921981
Pierson220082008
Gaza220012001
Mt Hamill120131968
Burchinal120241997
Cedar Valley119971969
Desmoines119741968
Panther120152010
Washington120031985
Maquoketa120241980
Alice119961976
Dinsdale119951969
Scranton120031967
Clare120192009

Willow Flycatcher Population Trend in Other States

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

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