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

Northern Parula Population Trend in New Jersey

All statesForest birds

Northern Parula in New Jersey has surged: up 381% on the route-weighted index since 1987.

+381%Since 1987TrendPercent 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 →
17Routes 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 →
33YearsYears 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 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 →

Northern Parula has surged in New Jersey: up 381% on the route-weighted index since 1987.

Northern Parula Population Forecast in New Jersey

If the recent trend holds, Northern Parula in New Jersey is projected to rise about 34% by 2029 — from 0.29 in 2024 to a central estimate of 0.38 (95% range 0.17–0.59). A 5-year backtest shows a typical error of ±24.4%, with 100% of held-out values landing inside the 95% band.

+34%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 →
0.38Projected 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 →
0.17–0.5995% 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 →
±24.4%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 New Jersey is projected to rise about 34% by 2029 — from 0.29 in 2024 to a central estimate of 0.38 (95% range 0.17–0.59). A 5-year backtest shows a typical error of ±24.4%, with 100% of held-out values landing inside the 95% band.19772029
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 →
20250.350.140.56
20260.360.150.57
20270.370.160.58
20280.380.170.58
20290.380.170.59

Northern Parula Survey Routes in New Jersey

Routes recording Northern Parula 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 →
Spraguetown719991999
Kemah Lake420241982
Winslow320102005
Bloomsbury220231997
Greenwich120012001
Six Points119921992
Toms River119961996
Albion120212011
Cape May Ch120052005
Pedricktown120122006
Sandbrook120192005
Holmansville120092004
Pedricktown 2120152013
Croton 2120082008
High Point120241977
Ramseysburg120191997
Pomona120242023

Northern Parula Population Trend in Other States

alabamaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsin

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