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

Louisiana Waterthrush Population Trend in Pennsylvania

All statesForest birds

Louisiana Waterthrush in Pennsylvania has surged: up 448% on the route-weighted index since 1968.

+448%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 →
95Routes 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 Louisiana Waterthrush 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 →

Louisiana Waterthrush has surged in Pennsylvania: up 448% on the route-weighted index since 1968.

Louisiana Waterthrush Population Forecast in Pennsylvania

If the recent trend holds, Louisiana Waterthrush in Pennsylvania is projected to fall about 16% by 2030 — from 0.78 in 2025 to a central estimate of 0.66 (95% range 0.43–0.89). A 5-year backtest shows a typical error of ±14.6%, with 100% of held-out values landing inside the 95% band.

-16%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 →
0.66Projected 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 →
0.43–0.8995% 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 →
±14.6%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, Louisiana Waterthrush in Pennsylvania is projected to fall about 16% by 2030 — from 0.78 in 2025 to a central estimate of 0.66 (95% range 0.43–0.89). A 5-year backtest shows a typical error of ±14.6%, 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 →
20260.630.400.86
20270.640.410.86
20280.640.410.87
20290.650.420.88
20300.660.430.89

Louisiana Waterthrush Survey Routes in Pennsylvania

Routes recording Louisiana Waterthrush 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 →
Laurel Hill1020251978
Ravensburg519751966
Warrens Mill520251971
Ramsey420251969
Duboistown420241991
Berwick420251985
Tussey Mtn.420251993
Broad Mtn.420251993
Ansonia420252004
Mawr Glen320251982
Hop Bottom320251967
Poyntelle320241973
Beaver320251990
Landisburg320251978
Roulette219811976
Logue219881976
Rosecrans220251969
Bow Bridge220131969
Marsh Hill220251983
Canadensis220251985
Susquehanna220251978
Rector219771966
Williamsburg220251989
Bald Eagle220221978
Doubling Gap219661966

Louisiana Waterthrush Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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