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

Northern Parula Population Trend in Pennsylvania

All statesForest birds

Northern Parula in Pennsylvania has surged: up 170% on the route-weighted index since 1968.

+170%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 →
90Routes 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 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 170% 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 2029, near 0.57 (95% range 0.41–0.73). A 5-year backtest shows a typical error of ±14.8%, with 80% of held-out values landing inside the 95% band.

+10%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 →
0.57Projected 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 →
0.41–0.7395% 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 →
±14.8%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 2029, near 0.57 (95% range 0.41–0.73). A 5-year backtest shows a typical error of ±14.8%, with 80% 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 →
20250.540.380.69
20260.540.390.70
20270.550.390.71
20280.560.400.72
20290.570.410.73

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 →
Ravensburg519661966
Warrens Mill520241972
Lynch420241971
Cherry Sprs420051974
Mawr Glen420131983
Honesdale420241975
Mill Run420241978
Doubling Gap319671966
Peru Mills320231966
Pine Gr Mill320241969
Normalville319701966
Ltl Pine Cr320241990
Russell City220241974
Little Marsh220132013
English Ctr219881987
Bald Eagle220241979
Waterstreet220241970
St College220151998
Mifflintown220241992
Jefferson220241970
Roulette 2220232023
Stoneybreak220181992
Wild Creek220242010
Whig Hill120221983
Sigel120221996

Northern Parula Population Trend in Other States

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

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