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Species · Pennsylvania · BBS 2025 Release · 1966–2024

Northern Waterthrush Population Trend in Pennsylvania

All statesForest birds

Northern Waterthrush in Pennsylvania has fallen sharply: down 61% on the route-weighted index since 1968.

-61%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 →
42Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern 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 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 →

Northern Waterthrush has fallen sharply in Pennsylvania: down 61% on the route-weighted index since 1968.

Northern Waterthrush Population Forecast in Pennsylvania

If the recent trend holds, Northern Waterthrush in Pennsylvania is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.08). A 5-year backtest shows a typical error of ±22.5%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.00–0.0895% 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 →
±22.5%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, Northern Waterthrush in Pennsylvania is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.08). A 5-year backtest shows a typical error of ±22.5%, 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 →
20250.020.000.08
20260.020.000.08
20270.020.000.08
20280.020.000.08
20290.020.000.08

Northern Waterthrush Survey Routes in Pennsylvania

Routes recording Northern 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 →
Rosecrans419791972
Ravensburg319781977
Roulette219741970
Logue219991999
Marsh Hill220241983
Waller220171979
Pocono Summit219971966
Virginia219731970
St College219771977
Clearfield219811980
Espyville119741974
Harmonsburg119801974
Ferris Crnrs120052002
Whig Hill119681968
Ellenton120161994
Teepleville119891966
Wyalusing119981990
Lynch120032003
N Washington119891989
Rothrock Sf120092009
Betula120042003
Russell City120071993
Ridgway120131988
Eldred120072004
Little Marsh119981998

Northern Waterthrush Population Trend in Other States

alaskaconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiorhode-islandvermontvirginiawashingtonwest-virginiawisconsinwyoming

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