BirdAnalyst
Species · Pennsylvania · BBS 2026 Release · 1966–2025

Brown Thrasher Population Trend in Pennsylvania

All statesForest birds

Brown Thrasher in Pennsylvania has declined: down 39% on the route-weighted index since 1968.

-39%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 →
135Routes 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 Brown Thrasher 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 Brown Thrasher in Pennsylvania. See the full index history below.

Brown Thrasher Population Forecast in Pennsylvania

If the recent trend holds, Brown Thrasher in Pennsylvania is projected to fall about 22% by 2030 — from 1.7 in 2025 to a central estimate of 1.3 (95% range 0.30–2.3). A 5-year backtest shows a typical error of ±27.3%, with 100% of held-out values landing inside the 95% band.

-22%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 →
1.3Projected 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 →
0.30–2.395% 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 →
±27.3%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, Brown Thrasher in Pennsylvania is projected to fall about 22% by 2030 — from 1.7 in 2025 to a central estimate of 1.3 (95% range 0.30–2.3). A 5-year backtest shows a typical error of ±27.3%, 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 →
20261.40.352.4
20271.40.342.4
20281.30.332.4
20291.30.312.4
20301.30.302.3

Brown Thrasher Survey Routes in Pennsylvania

Routes recording Brown Thrasher 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 →
Pine Gr Mill1020251967
Stoneybreak820251992
Waller620251977
Naginey620251971
Jefferson620251966
Mt Gretna 2620222008
Berwick620251985
St College520251969
Normalville519741966
Needmore519911966
Ellenton520251985
Jacobus520251986
Ramsey420251968
Logue420251971
Rosecrans420251969
Plesant Grov420241966
Munson420251979
Mifflintown420251966
Harrisville420231995
Doylesburg420232009
Drehersville 2420252002
Mill Run420251978
Slippery Rk319921970
Little Marsh320241972
Marsh Hill320251985

Brown Thrasher Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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