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

Blue-winged Warbler Population Trend in New Jersey

All statesForest birds

Blue-winged Warbler in New Jersey has collapsed: down 90% on the route-weighted index since 1968.

-90%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 →
33Routes 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 Blue-winged 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 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 →

Blue-winged Warbler has collapsed in New Jersey: down 90% on the route-weighted index since 1968.

Blue-winged Warbler Population Forecast in New Jersey

If the recent trend holds, Blue-winged Warbler in New Jersey is projected to fall about 56% by 2029 — from 0.14 in 2024 to a central estimate of 0.06 (95% range 0.00–0.79). A 5-year backtest shows a typical error of ±112%, with 100% of held-out values landing inside the 95% band.

-56%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 →
0.06Projected 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 →
0.00–0.7995% 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 →
±112%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, Blue-winged Warbler in New Jersey is projected to fall about 56% by 2029 — from 0.14 in 2024 to a central estimate of 0.06 (95% range 0.00–0.79). A 5-year backtest shows a typical error of ±112%, 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 →
20250.130.000.86
20260.120.000.85
20270.100.000.83
20280.080.000.81
20290.060.000.79

Blue-winged Warbler Survey Routes in New Jersey

Routes recording Blue-winged 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 →
Albion419921966
Del Haven319911991
Spraguetown 2320042000
Six Points220122012
Holmansville219961969
High Point220211977
Gillette220241989
Mt Misery219791976
Winslow220021989
Greenwich119731973
Toms River119971976
Ancora119751966
Bennett Mill120001966
Sandbrook120171970
New Bedford120051971
Croton120071970
Hope119931976
Midvale119991970
Kemah Lake120191980
Bloomsbury120241987
Dover120231977
Pottersville119981979
Keyport120091990
Cranbury120051994
Roosevelt119971986

Blue-winged Warbler Population Trend in Other States

alabamaarkansasconnecticutdelawaregeorgiaillinoisindianaiowakentuckymarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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