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

Willow Flycatcher Population Trend in Wisconsin

All statesAerial insectivores

Willow Flycatcher in Wisconsin has surged: up 114% on the route-weighted index since 1968.

+114%Since 1968TrendPercent 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 →
77Routes 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 →
58YearsYears 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 WisconsinNotable 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 Wisconsin: up 114% on the route-weighted index since 1968.

Willow Flycatcher Population Forecast in Wisconsin

If the recent trend holds, Willow Flycatcher in Wisconsin is projected to rise about 22% by 2029 — from 1.3 in 2024 to a central estimate of 1.6 (95% range 1.1–2.1). A 5-year backtest shows a typical error of ±30.9%, with 80% of held-out values landing inside the 95% band.

+22%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 →
1.6Projected 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 →
1.1–2.195% 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 →
±30.9%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 Wisconsin is projected to rise about 22% by 2029 — from 1.3 in 2024 to a central estimate of 1.6 (95% range 1.1–2.1). A 5-year backtest shows a typical error of ±30.9%, with 80% of held-out values landing inside the 95% band.19662029
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 →
20251.51.12.0
20261.61.12.1
20271.61.12.1
20281.61.12.1
20291.61.12.1

Willow Flycatcher Survey Routes in Wisconsin

Routes recording Willow Flycatcher in Wisconsin.
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 →
Paris920241966
Gilmanton820241967
Hebron820241966
Viroqua720241966
Pardeeville620241985
Wiota620241966
Fall River520241989
Eden520241967
Highland520241998
Annaton520241998
Beloit520241998
Omro420011966
Kendall420231970
Hudson320241966
Dresser320231966
Stratford320211996
New Lisbon320241967
N Freedom320241966
Brownsville320211966
Buena Vista320232001
Grimms320211998
Briggsville320241999
Chaffey220161998
Cochrane220241966
Cadott220241980

Willow Flycatcher Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawyoming

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