BirdAnalyst
Species · New Jersey · BBS 2025 Release · 1966–2024

Prothonotary Warbler Population Trend in New Jersey

All statesForest birds

Prothonotary Warbler in New Jersey has surged: up 465% on the route-weighted index since 1986.

+465%Since 1986TrendPercent 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 →
13Routes 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 →
28YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Prothonotary Warbler Trends in New JerseyNotable 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 →

Prothonotary Warbler has surged in New Jersey: up 465% on the route-weighted index since 1986.

Prothonotary Warbler Population Forecast in New Jersey

If the recent trend holds, Prothonotary Warbler in New Jersey is projected to fall about 23% by 2029 — from 0.33 in 2024 to a central estimate of 0.26 (95% range 0.12–0.40). A 5-year backtest shows a typical error of ±36.2%, with 60% of held-out values landing inside the 95% band.

-23%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 →
0.26Projected 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 →
0.12–0.4095% 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 →
±36.2%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, Prothonotary Warbler in New Jersey is projected to fall about 23% by 2029 — from 0.33 in 2024 to a central estimate of 0.26 (95% range 0.12–0.40). A 5-year backtest shows a typical error of ±36.2%, with 60% of held-out values landing inside the 95% band.19792029
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 →
20250.240.100.38
20260.240.100.38
20270.250.100.39
20280.250.110.39
20290.260.120.40

Prothonotary Warbler Survey Routes in New Jersey

Routes recording Prothonotary Warbler in New Jersey.
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 →
Pomona520241987
Cape May Ch320111993
Estell Manor220222021
Pedricktown220102000
Woodbury Hgt120181986
Six Points120032003
Albion119921992
Bennett Mill119961996
Winslow120241989
Pedricktown 2120182018
Ramseysburg120052005
Friendship120241991
Villas119811979

Prothonotary Warbler Population Trend in Other States

alabamaarkansasdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmichiganminnesotamississippimissourinew-yorknorth-carolinaohiooklahomapennsylvaniasouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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