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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Brown-headed Cowbird Population Trend in Pennsylvania

All statesGeneralists

Brown-headed Cowbird in Pennsylvania has declined: down 38% on the route-weighted index since 1968.

-38%Since 1968
137Routes In State
58Years

Notable Brown-headed Cowbird Trends in Pennsylvania

No notable trend signals for Brown-headed Cowbird in Pennsylvania. See the full index history below.

Brown-headed Cowbird Population Forecast in Pennsylvania

If the recent trend holds, Brown-headed Cowbird in Pennsylvania is projected to stay roughly flat through 2029, near 5.3 (95% range 2.9–7.7). A 5-year backtest shows a typical error of ±10.3%, with 100% of held-out values landing inside the 95% band.

-7%Change by 2029
5.3Projected 2029 index
2.9–7.795% range
±10.3%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
20255.63.28.0
20265.53.18.0
20275.53.17.9
20285.43.07.8
20295.32.97.7

Brown-headed Cowbird Survey Routes in Pennsylvania

Routes recording Brown-headed Cowbird in Pennsylvania.
Big Flat3419811966
West Grove2819961966
Jacobus2820241986
Stoneybreak2520241992
Quakertown2219891970
Beaver1920241969
Mount Joy1920241978
Mill Run1820241978
Brunnerville1720091969
Chatham1620241997
Wyalusing1620241985
Ryde1520051968
Sugar Grove1520231980
Harmonsburg1420231966
Middletown1420241973
Scheafferstn1420011966
Bendersville1420241990
Plesant Grov1320241966
Sardis1319741967
Pottstown1319871966
Drehersville1319991966
Schaefferstown 21320242002
Virginia1220241969
Geeseytown1220241987
Mt Gretna 21220222002

Brown-headed Cowbird 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.