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Species · Maine · BBS 2025 Release · 1966–2024

Black-throated Green Warbler Population Trend in Maine

All statesForest birds

Black-throated Green Warbler in Maine has increased: up 38% on the route-weighted index since 1968.

+38%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 →
58YearsYears 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 51% by 2029 — from 4.1 in 2024 to a central estimate of 6.2 (95% range 2.2–10). A 5-year backtest shows a typical error of ±42.2%, with 100% of held-out values landing inside the 95% band.

+51%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 →
6.2Projected 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 →
2.2–1095% 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 →
±42.2%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 51% by 2029 — from 4.1 in 2024 to a central estimate of 6.2 (95% range 2.2–10). A 5-year backtest shows a typical error of ±42.2%, 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 →
20256.02.09.9
20266.02.110.0
20276.12.110
20286.12.210
20296.22.210

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
Eastbrook2420241971
Wilson Mills2120241983
Seboomook Lk2020141974
Brooks1620191977
Nesowadnehun1520211990
Grnd Lk Strm1320001966
Andover1320212010
Medway1120181976
Topsfield1119961978
Castine820061976
Deblois820071966
Telos820061995
East Troy720191972
Hermon720191966
Moose River720081983
Charleston720191975
Ludlow719981968
Forest Sta620001966
Horse Mtn620111983
Ft Fairfield620051993
Weeks Brook620161995
Brownfield620092009

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 2026-05-22.