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Species · Maine · BBS 2026 Release · 1966–2025

Black-throated Green Warbler Population Trend in Maine

All statesForest birds

Black-throated Green Warbler in Maine has increased: up 41% on the route-weighted index since 1968.

+41%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 →
78Routes 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 →
59YearsYears 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 MaineNotable 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 Maine. See the full index history below.

Black-throated Green Warbler Population Forecast in Maine

If the recent trend holds, Black-throated Green Warbler in Maine is projected to rise about 56% by 2030 — from 3.9 in 2025 to a central estimate of 6.1 (95% range 2.1–10). A 5-year backtest shows a typical error of ±54.3%, with 100% of held-out values landing inside the 95% band.

+56%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 →
6.1Projected 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 →
2.1–1095% 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 →
±54.3%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 Maine is projected to rise about 56% by 2030 — from 3.9 in 2025 to a central estimate of 6.1 (95% range 2.1–10). A 5-year backtest shows a typical error of ±54.3%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20265.91.99.8
20275.92.09.9
20286.02.09.9
20296.02.110.0
20306.12.110

Black-throated Green Warbler Survey Routes in Maine

Routes recording Black-throated Green Warbler in Maine.
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 →
Northfield8519811976
Cooper3020211975
Waite2719771977
Seboomook Lk2020141974
Nesowadnehun1520211990
Eastbrook1420251971
Grnd Lk Strm1320001966
Andover1320212010
Brooks1120211977
Topsfield1119961978
Wilson Mills1020251983
Winn920251969
Castine820061976
Deblois820071966
Telos820061995
East Troy720211972
Moose River720081983
Ludlow719981968
Hancock620251969
Carrying Pl620251979
Medway620251976
Forest Sta620001966
Horse Mtn620111983
Ft Fairfield620051993
Weeks Brook620161995

Black-throated Green Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaindianakentuckymarylandmassachusettsmichiganminnesotamissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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