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

Northern Parula Population Trend in Pennsylvania

All statesForest birds

Northern Parula in Pennsylvania has surged: up 146% on the route-weighted index since 1968.

+146%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 →
91Routes 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 Northern Parula 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 →

Northern Parula has surged in Pennsylvania: up 146% on the route-weighted index since 1968.

Northern Parula Population Forecast in Pennsylvania

If the recent trend holds, Northern Parula in Pennsylvania is projected to stay roughly flat through 2030, near 0.58 (95% range 0.42–0.73). A 5-year backtest shows a typical error of ±12.7%, with 80% of held-out values landing inside the 95% band.

+2%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 →
0.58Projected 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 →
0.42–0.7395% 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 →
±12.7%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, Northern Parula in Pennsylvania is projected to stay roughly flat through 2030, near 0.58 (95% range 0.42–0.73). A 5-year backtest shows a typical error of ±12.7%, with 80% 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 →
20260.550.390.70
20270.550.400.71
20280.560.400.72
20290.570.410.73
20300.580.420.73

Northern Parula Survey Routes in Pennsylvania

Routes recording Northern Parula 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 →
Warrens Mill620251972
Ltl Pine Cr620251990
Ravensburg519661966
Cherry Sprs420051974
Clear Spring420251980
Honesdale320251975
Doubling Gap319671966
Naginey320251974
Jefferson320251970
Normalville319701966
Mill Run320251978
Wild Creek320252010
Little Marsh220132013
English Ctr219881987
Mawr Glen220251983
Geeseytown220251989
Bald Eagle220251979
Waterstreet220241970
St College220151998
Pine Gr Mill220251969
Mifflintown220241992
Garrett220251966
Roulette 2220232023
Stoneybreak220181992
Espyville120252025

Northern Parula Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsin

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