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

Tree Swallow Population Trend in Pennsylvania

All statesAerial insectivores

Tree Swallow in Pennsylvania has surged: up 198% on the route-weighted index since 1968.

+198%Since 1968
127Routes In State
58Years

Notable Tree Swallow Trends in Pennsylvania

long arc increasecomputed index

Tree Swallow has surged in Pennsylvania: up 198% on the route-weighted index since 1968.

Tree Swallow Population Forecast in Pennsylvania

If the recent trend holds, Tree Swallow in Pennsylvania is projected to rise about 74% by 2029 — from 3.5 in 2024 to a central estimate of 6.1 (95% range 2.9–9.3). A 5-year backtest shows a typical error of ±106.3%, with 20% of held-out values landing inside the 95% band.

+74%Change by 2029
6.1Projected 2029 index
2.9–9.395% range
±106.3%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
20255.82.79.0
20265.92.79.1
20276.02.89.2
20286.02.99.2
20296.12.99.3

Tree Swallow Survey Routes in Pennsylvania

Routes recording Tree Swallow in Pennsylvania.
Brunnerville 22920242010
Ryde2720051981
Betula2020221974
Sugar Grove1720241980
Susquehanna1620241971
Hometown1320241967
Ellenton1220241984
Rush1120241970
Drehersville1119981983
Doe Run1120241979
Berwick1120241986
Marsh Hill1020241983
Honesdale1020241973
Schaefferstown 21020242002
Akeley919791968
Roulette920211971
Hop Bottom920241967
Portersville919881976
Pine Gr Mill920241985
Pottersdale820241988
Logue820231974
Brunnerville820091973
Canadensis720241969
Poyntelle720241969
Ltl Pine Cr720241990

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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