BirdAnalyst
Species · Pennsylvania · BBS 2025 Release · 1966–2024

Brown Thrasher Population Trend in Pennsylvania

All statesGeneralists

Brown Thrasher in Pennsylvania has declined: down 35% on the route-weighted index since 1968.

-35%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 →
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 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 17% by 2029 — from 1.6 in 2024 to a central estimate of 1.3 (95% range 0.28–2.3). A 5-year backtest shows a typical error of ±32%, with 100% of held-out values landing inside the 95% band.

-17%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 →
1.3Projected 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 →
0.28–2.395% 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 →
±32%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 17% by 2029 — from 1.6 in 2024 to a central estimate of 1.3 (95% range 0.28–2.3). A 5-year backtest shows a typical error of ±32%, 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 →
20251.40.332.4
20261.30.322.4
20271.30.312.4
20281.30.302.3
20291.30.282.3

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 →
Poyntelle1320181969
Rush720241970
Mt Gretna 2620222008
Drehersville 2620242002
Stoneybreak620241992
Berwick620241985
Sigel520241981
Mawr Glen520241966
Waller520241977
Millville520241969
St College520241969
Peru Mills520231966
Normalville519741966
Needmore519911966
Elizabethvil520241995
Susquehanna420241971
Plesant Grov420241966
Harrisville420231995
Doylesburg420232009
Slippery Rk319921970
Ramsey320231968
Little Marsh320241972
Marsh Hill320241985
Hop Bottom320211967
Beaver320231969

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 2026-05-22.