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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Kentucky Warbler Population Trend in Pennsylvania

All statesForest birds

Kentucky Warbler in Pennsylvania has collapsed: down 91% on the route-weighted index since 1968.

-91%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 →
71Routes 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 Kentucky 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 declinecomputed 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 →

Kentucky Warbler has collapsed in Pennsylvania: down 91% on the route-weighted index since 1968.

Kentucky Warbler Population Forecast in Pennsylvania

If the recent trend holds, Kentucky Warbler in Pennsylvania is projected to fall about 44% by 2030 — from 0.06 in 2025 to a central estimate of 0.03 (95% range 0.00–0.20). A 5-year backtest shows a typical error of ±116.5%, with 100% of held-out values landing inside the 95% band.

-44%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 →
0.03Projected 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 →
0.00–0.2095% 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 →
±116.5%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, Kentucky Warbler in Pennsylvania is projected to fall about 44% by 2030 — from 0.06 in 2025 to a central estimate of 0.03 (95% range 0.00–0.20). A 5-year backtest shows a typical error of ±116.5%, 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 →
20260.050.000.23
20270.050.000.22
20280.040.000.22
20290.040.000.21
20300.030.000.20

Kentucky Warbler Survey Routes in Pennsylvania

Routes recording Kentucky 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 →
Normalville719701966
Jefferson420251966
Tussey Mtn.319941994
Rector319771966
Sigel220011981
Portersville219761974
Duvall220211975
Sardis219741970
Kaylor220211969
Patton219971992
Geeseytown220071992
Scheafferstn219991969
Needmore219901971
Labott219821975
West Grove219781966
Slippery Rk119751975
Clover120191993
Ferris Crnrs119711971
Wyalusing119901990
Berwick120001985
Teepleville120102010
Rothrock Sf120181998
N Washington119971968
Broad Mtn.120242024
Betula120092009

Kentucky Warbler Population Trend in Other States

alabamaarkansasdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmississippimissourinew-jerseynew-yorknorth-carolinaohiooklahomasouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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