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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Cerulean Warbler Population Trend in Pennsylvania

All statesForest birds

Cerulean Warbler in Pennsylvania has held roughly steady: down 1% on the route-weighted index since 1968.

-1%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 →
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 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 fall about 22% by 2029 — from 0.24 in 2024 to a central estimate of 0.18 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±61%, with 100% of held-out values landing inside the 95% band.

-22%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 →
0.18Projected 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 →
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 →
±61%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 fall about 22% by 2029 — from 0.24 in 2024 to a central estimate of 0.18 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±61%, 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 →
20250.190.000.40
20260.190.000.40
20270.190.000.40
20280.190.000.40
20290.180.000.39

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 →
Landisburg620241978
Carsonville519971997
Roulette420212021
Geeseytown420241987
Broad Mtn.420211997
Rector319771966
Peru Mills320242001
N Washington220021970
Eldred220041995
Portersville219761976
Sardis219741968
St College220091981
Pine Gr Mill220141987
Peters Mt219941994
Jefferson220241966
Sproul Sf-B220152003
Espyville120211967
Clover120231988
Harmonsburg119891989
Whig Hill120221991
Akeley119741974
Teepleville120061999
Sigel120022002
Lynch120001968
N Pine Grove120061974

Cerulean Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaillinoisindianakentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomatennesseevermontvirginiawest-virginiawisconsin

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