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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Willow Flycatcher Population Trend in Pennsylvania

All statesAerial insectivores

Willow Flycatcher in Pennsylvania has surged: up 96% on the route-weighted index since 1968.

+96%Since 1968
118Routes In State
58Years

Notable Willow Flycatcher Trends in Pennsylvania

long arc increasecomputed index

Willow Flycatcher has surged in Pennsylvania: up 96% on the route-weighted index since 1968.

Willow Flycatcher Population Forecast in Pennsylvania

If the recent trend holds, Willow Flycatcher in Pennsylvania is projected to rise about 63% by 2029 — from 1.2 in 2024 to a central estimate of 2.0 (95% range 1.0–3.0). A 5-year backtest shows a typical error of ±73.6%, with 60% of held-out values landing inside the 95% band.

+63%Change by 2029
2.0Projected 2029 index
1.0–3.095% range
±73.6%Backtest error
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 index95% low95% high
20251.90.962.9
20262.00.982.9
20272.00.993.0
20282.01.03.0
20292.01.03.0

Willow Flycatcher Survey Routes in Pennsylvania

Routes recording Willow Flycatcher in Pennsylvania.
West Grove1419961967
Harmonsburg1220231966
Jefferson720241966
Poyntelle620241975
Beaver620241978
Plesant Grov620241970
Kaylor620241995
Drehersville619991966
Drehersville 2620242000
Ferris Crnrs520241966
Waller520241974
Quakertown519891972
Teepleville420241966
Roulette420161989
Martinsburg420241988
Clover320241988
Millville320241974
Honesdale320241972
Portersville319881974
Parkwood320231967
Kittanning320231973
Brunnerville320091970
Doe Run320241969
Mt Gretna 2320192015
Schaefferstown 2320242008

Willow Flycatcher Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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