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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Cliff Swallow Population Trend in Pennsylvania

All statesAerial insectivores

Cliff Swallow in Pennsylvania has declined: down 50% on the route-weighted index since 1968.

-50%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 →
85Routes 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 Cliff Swallow 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 Cliff Swallow in Pennsylvania. See the full index history below.

Cliff Swallow Population Forecast in Pennsylvania

If the recent trend holds, Cliff Swallow in Pennsylvania is projected to rise about 33% by 2030 — from 0.51 in 2025 to a central estimate of 0.67 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±35.9%, with 100% of held-out values landing inside the 95% band.

+33%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 →
0.67Projected 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 →
0.00–1.695% 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 →
±35.9%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, Cliff Swallow in Pennsylvania is projected to rise about 33% by 2030 — from 0.51 in 2025 to a central estimate of 0.67 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±35.9%, 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 →
20260.720.001.6
20270.710.001.6
20280.700.001.6
20290.690.001.6
20300.670.001.6

Cliff Swallow Survey Routes in Pennsylvania

Routes recording Cliff Swallow 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 →
Harrisville1820112011
Garrett1320251975
Eldred1120221981
Carsonville1019961989
Pocono Summit920251966
Russell City820231970
Ltl Pine Cr820211996
Munson720251987
Mill Run720251987
Roulette620161977
West Grove619921976
Ridgway519671967
Rosecrans520221969
Susquehanna520241971
New Ringgold520151966
Clearfield519931971
Rasselas420162006
Marsh Hill420221984
Ryde419971978
Wild Creek420231988
Espyville320241967
Lynch320171971
Pottersdale319971971
Betula320221973
Little Marsh320152001

Cliff Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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