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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Black-and-white Warbler Population Trend in Pennsylvania

All statesForest birds

Black-and-white Warbler in Pennsylvania has surged: up 246% on the route-weighted index since 1968.

+246%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 Black-and-white Warbler 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 →

Black-and-white Warbler has surged in Pennsylvania: up 246% on the route-weighted index since 1968.

Black-and-white Warbler Population Forecast in Pennsylvania

If the recent trend holds, Black-and-white Warbler in Pennsylvania is projected to fall about 34% by 2029 — from 3.0 in 2024 to a central estimate of 2.0 (95% range 1.3–2.6). A 5-year backtest shows a typical error of ±25.2%, with 40% of held-out values landing inside the 95% band.

-34%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 →
2.0Projected 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 →
1.3–2.695% 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 →
±25.2%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, Black-and-white Warbler in Pennsylvania is projected to fall about 34% by 2029 — from 3.0 in 2024 to a central estimate of 2.0 (95% range 1.3–2.6). A 5-year backtest shows a typical error of ±25.2%, with 40% 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 →
20251.91.32.6
20261.91.32.6
20272.01.32.6
20282.01.32.6
20292.01.32.6

Black-and-white Warbler Survey Routes in Pennsylvania

Routes recording Black-and-white Warbler 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 →
Duboistown2220241987
Poyntelle2020241973
Roulette 21620242022
Broad Mtn.1620241994
Roulette1520211976
Tussey Mtn.1520241993
Ansonia1520242002
Mill Run1420241978
Odin1120241974
Munson1120241979
Ltl Pine Cr1120241990
Starlight 2920242000
Laurel Hill920241978
Pottersdale820241968
Ryde820051968
Sproul Sf-A820242002
Marsh Hill720241983
Geeseytown720241987
St College720241969
English Ctr619891988
Cherry Sprs620231974
Rothrock Sf620191992
Susquehanna520241971
Ellenton520241982
Greentown420241973

Black-and-white Warbler Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawaregeorgiaillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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