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Species · Pennsylvania · BBS 2026 Release · 1966–2025

Swainson's Thrush Population Trend in Pennsylvania

All statesForest birds

Swainson's Thrush in Pennsylvania has collapsed: down 76% on the route-weighted index since 1969.

-76%Since 1969TrendPercent 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 →
17Routes 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 →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Swainson's Thrush 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 →

Swainson's Thrush has collapsed in Pennsylvania: down 75% on the route-weighted index since 1969.

Swainson's Thrush Population Forecast in Pennsylvania

If the recent trend holds, Swainson's Thrush in Pennsylvania is projected to stay roughly flat through 2030, near 0.04 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±106.1%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.04Projected 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 →
0.00–0.1095% 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 →
±106.1%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, Swainson's Thrush in Pennsylvania is projected to stay roughly flat through 2030, near 0.04 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±106.1%, with 80% 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 →
20260.040.000.09
20270.040.000.09
20280.040.000.09
20290.040.000.09
20300.040.000.10

Swainson's Thrush Survey Routes in Pennsylvania

Routes recording Swainson's Thrush 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 →
Cherry Sprs620211974
Whig Hill219881966
Marsh Hill120051986
Ellenton120131982
Lynch120241975
Lovelton120042004
Odin120151973
Betula120072007
Russell City120251994
Eldred120151990
Rasselas120162016
Roulette120161988
Logue120162016
Virginia119781978
English Ctr119741971
Laurel Hill119901990
Mawr Glen119751968

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonsouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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