BirdAnalyst
Species · New Jersey · BBS 2026 Release · 1966–2025

Cerulean Warbler Population Trend in New Jersey

All statesForest birds

Cerulean Warbler in New Jersey has risen sharply: up 70% on the route-weighted index since 1980.

+70%Since 1980TrendPercent 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 →
5Routes 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 →
36YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cerulean 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 →

No notable trend signals for Cerulean Warbler in New Jersey. See the full index history below.

Cerulean Warbler Population Forecast in New Jersey

If the recent trend holds, Cerulean Warbler in New Jersey is projected to rise about 213% by 2030 — from 0.06 in 2025 to a central estimate of 0.17 (95% range 0.02–0.33). A 5-year backtest shows a typical error of ±96.9%, with 100% of held-out values landing inside the 95% band.

+213%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 →
0.17Projected 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 →
0.02–0.3395% 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 →
±96.9%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, Cerulean Warbler in New Jersey is projected to rise about 213% by 2030 — from 0.06 in 2025 to a central estimate of 0.17 (95% range 0.02–0.33). A 5-year backtest shows a typical error of ±96.9%, with 100% of held-out values landing inside the 95% band.19782030
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 →
20260.170.010.33
20270.170.010.33
20280.170.010.33
20290.170.010.33
20300.170.020.33

Cerulean Warbler Survey Routes in New Jersey

Routes recording Cerulean 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 →
Kemah Lake320141991
Midvale119791979
Bloomsbury119781978
High Point120251988
Dover119801980

Cerulean Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaillinoisindianakentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-yorknorth-carolinaohiooklahomapennsylvaniatennesseevermontvirginiawest-virginiawisconsin

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