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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Hermit Thrush Population Trend in Pennsylvania

All statesForest birds

Hermit Thrush in Pennsylvania has surged: up 170% on the route-weighted index since 1968.

+170%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 →
81Routes 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 Hermit 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 increasecomputed 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 →

Hermit Thrush has surged in Pennsylvania: up 170% on the route-weighted index since 1968.

Hermit Thrush Population Forecast in Pennsylvania

If the recent trend holds, Hermit Thrush in Pennsylvania is projected to rise about 82% by 2029 — from 1.3 in 2024 to a central estimate of 2.5 (95% range 1.2–3.8). A 5-year backtest shows a typical error of ±138.7%, with 0% of held-out values landing inside the 95% band.

+82%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 →
2.5Projected 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 →
1.2–3.895% 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 →
±138.7%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, Hermit Thrush in Pennsylvania is projected to rise about 82% by 2029 — from 1.3 in 2024 to a central estimate of 2.5 (95% range 1.2–3.8). A 5-year backtest shows a typical error of ±138.7%, with 0% 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 →
20252.41.13.6
20262.41.13.7
20272.41.13.7
20282.41.13.7
20292.51.23.8

Hermit Thrush Survey Routes in Pennsylvania

Routes recording Hermit 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 →
Odin1420241973
Lynch1120241968
Rasselas1120221969
Marsh Hill1120241983
Russell City820241968
Ansonia820242002
Little Marsh720241969
Cherry Sprs720231974
Starlight719991980
Ellenton620241982
Sproul Sf-B620242002
Ridgway520181966
Pocono Summit520241967
Sproul Sf-A520242002
N Pine Grove420241969
Roulette420211972
Susquehanna420241972
New Ringgold420081983
Sugar Grove420231995
Ltl Pine Cr420241990
Duboistown420211987
Sigel320211991
Arnot320241971
Logue320231970
Canadensis320241977

Hermit Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonrhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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