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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Acadian Flycatcher Population Trend in Pennsylvania

All statesAerial insectivores

Acadian Flycatcher in Pennsylvania has surged: up 257% on the route-weighted index since 1968.

+257%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 →
112Routes 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 Acadian Flycatcher Trends in PennsylvaniaNotable 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 →

Acadian Flycatcher has surged in Pennsylvania: up 257% on the route-weighted index since 1968.

Acadian Flycatcher Population Forecast in Pennsylvania

If the recent trend holds, Acadian Flycatcher in Pennsylvania is projected to rise about 13% by 2029 — from 2.2 in 2024 to a central estimate of 2.5 (95% range 1.7–3.4). A 5-year backtest shows a typical error of ±14.7%, with 100% of held-out values landing inside the 95% band.

+13%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 →
2.5Projected 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 →
1.7–3.495% 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 →
±14.7%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, Acadian Flycatcher in Pennsylvania is projected to rise about 13% by 2029 — from 2.2 in 2024 to a central estimate of 2.5 (95% range 1.7–3.4). A 5-year backtest shows a typical error of ±14.7%, with 100% 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 →
20252.41.63.3
20262.51.63.3
20272.51.63.3
20282.51.73.3
20292.51.73.4

Acadian Flycatcher Survey Routes in Pennsylvania

Routes recording Acadian Flycatcher in Pennsylvania.
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 →
Broad Mtn.2020241993
Laurel Hill1620241978
Tussey Mtn.1620241993
Landisburg1420241978
Stoneybreak1420241992
St College920241976
N Washington820241973
Harmonsburg720231979
Martinsburg720241988
Warrens Mill720241972
Mill Run720241978
Ravensburg619711971
Shelocta620241968
Clear Spring620241966
Beaver520241981
Sardis519741970
Peru Mills520241966
Duvall420211974
Parkwood420241983
Kittanning420241973
Kaylor420241995
Margaret420241970
Needmore419911966
Harrisville420231997
Rothrock Sf420191992

Acadian Flycatcher Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomarhode-islandsouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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