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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Cerulean Warbler Population Trend in Pennsylvania

All statesForest birds

Cerulean Warbler in Pennsylvania has edged down: down 10% on the route-weighted index since 1968.

-10%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 →
77Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cerulean 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 →

No notable trend signals for Cerulean Warbler in Pennsylvania. See the full index history below.

Cerulean Warbler Population Forecast in Pennsylvania

If the recent trend holds, Cerulean Warbler in Pennsylvania is projected to rise about 72% by 2030 — from 0.10 in 2025 to a central estimate of 0.18 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±42%, with 100% of held-out values landing inside the 95% band.

+72%Change by 2030TrendPercent 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 →
0.18Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.3995% 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 →
±42%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, Cerulean Warbler in Pennsylvania is projected to rise about 72% by 2030 — from 0.10 in 2025 to a central estimate of 0.18 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±42%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.180.000.39
20270.180.000.39
20280.180.000.39
20290.180.000.39
20300.180.000.39

Cerulean Warbler Survey Routes in Pennsylvania

Routes recording Cerulean 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 →
Carsonville519971997
Roulette420212021
Broad Mtn.420211997
Rector319771966
Peru Mills320242001
Clover220251988
N Washington220021970
Eldred220041995
Portersville219761976
Sardis219741968
Geeseytown220251987
St College220091981
Peters Mt219941994
Jefferson220241966
Sproul Sf-B220152003
Espyville120211967
Harmonsburg119891989
Whig Hill120221991
Akeley119741974
Teepleville120061999
Sigel120022002
Lynch120001968
N Pine Grove120061974
Pottersdale119751975
Odin120131982

Cerulean Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaillinoisindianakentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomatennesseevermontvirginiawest-virginiawisconsin

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.