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

Black-throated Green Warbler Population Trend in New Jersey

All statesForest birds

Black-throated Green Warbler in New Jersey has declined: down 46% on the route-weighted index since 1979.

-46%Since 1979TrendPercent 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 →
21YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-throated Green 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 Black-throated Green Warbler in New Jersey. See the full index history below.

Black-throated Green Warbler Population Forecast in New Jersey

If the recent trend holds, Black-throated Green Warbler in New Jersey is projected to stay roughly flat through 2021, near 0.05 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±61.1%, with 80% of held-out values landing inside the 95% band.

n/aChange by 2021TrendPercent 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 →
0.05Projected 2021 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1395% 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 →
±61.1%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, Black-throated Green Warbler in New Jersey is projected to stay roughly flat through 2021, near 0.05 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±61.1%, with 80% of held-out values landing inside the 95% band.19662021
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 →
20170.050.000.13
20180.050.000.13
20190.050.000.13
20200.050.000.13
20210.050.000.13

Black-throated Green Warbler Survey Routes in New Jersey

Routes recording Black-throated Green 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 →
Toms River119661966
Kemah Lake120161989
High Point120111990
Friendship119971997
Pomona119951978

Black-throated Green Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaindianakentuckymainemarylandmassachusettsmichiganminnesotamissourinew-hampshirenew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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