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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Black-billed Cuckoo Population Trend in Pennsylvania

All statesGeneralists

Black-billed Cuckoo in Pennsylvania has fallen sharply: down 73% on the route-weighted index since 1968.

-73%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 →
126Routes 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-billed Cuckoo 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 →

Black-billed Cuckoo has fallen sharply in Pennsylvania: down 73% on the route-weighted index since 1968.

Black-billed Cuckoo Population Forecast in Pennsylvania

If the recent trend holds, Black-billed Cuckoo in Pennsylvania is projected to rise about 220% by 2029 — from 0.08 in 2024 to a central estimate of 0.25 (95% range 0.00–0.84). A 5-year backtest shows a typical error of ±97.9%, with 100% of held-out values landing inside the 95% band.

+220%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 →
0.25Projected 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 →
0.00–0.8495% 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 →
±97.9%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-billed Cuckoo in Pennsylvania is projected to rise about 220% by 2029 — from 0.08 in 2024 to a central estimate of 0.25 (95% range 0.00–0.84). A 5-year backtest shows a typical error of ±97.9%, 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 →
20250.290.000.87
20260.280.000.86
20270.270.000.85
20280.260.000.84
20290.250.000.84

Black-billed Cuckoo Survey Routes in Pennsylvania

Routes recording Black-billed Cuckoo 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 →
Big Flat1119811975
Rasselas1020221971
Betula820221974
Starlight619921970
Wyalusing520231988
Sproul Sf-B520232005
Ryde420051970
Jeannette420161979
Eldred320151988
Kittanning320191972
Peru Mills320081967
Clearfield320021967
Doe Run319911972
Lovelton320162005
Akeley219791966
Sigel220211989
N Washington220211968
Rosecrans220231972
English Ctr219771966
Austinville220231970
Rush220151970
Waller220161981
Pocono Summit220151968
Hop Bottom220141967
Greentown220221973

Black-billed Cuckoo Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomarhode-islandsouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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