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Species · Maine · BBS 2025 Release · 1966–2024

Black-throated Blue Warbler Population Trend in Maine

All statesForest birds

Black-throated Blue Warbler in Maine has surged: up 96% on the route-weighted index since 1969.

+96%Since 1969TrendPercent 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 →
75Routes 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 →
56YearsYears 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 Blue 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 →

long arc increasecomputed 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 →

Black-throated Blue Warbler has surged in Maine: up 96% on the route-weighted index since 1969.

Black-throated Blue Warbler Population Forecast in Maine

If the recent trend holds, Black-throated Blue Warbler in Maine is projected to rise about 39% by 2029 — from 2.2 in 2024 to a central estimate of 3.1 (95% range 1.7–4.4). A 5-year backtest shows a typical error of ±44.8%, with 80% of held-out values landing inside the 95% band.

+39%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 →
3.1Projected 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 →
1.7–4.495% 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 →
±44.8%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 Blue Warbler in Maine is projected to rise about 39% by 2029 — from 2.2 in 2024 to a central estimate of 3.1 (95% range 1.7–4.4). A 5-year backtest shows a typical error of ±44.8%, with 80% 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 →
20252.91.64.3
20263.01.64.3
20273.01.64.3
20283.01.74.4
20293.11.74.4

Black-throated Blue Warbler Survey Routes in Maine

Routes recording Black-throated Blue 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 →
Charleston2020191977
Horse Mtn1620111983
Brooks1220191977
Waite1219771977
Hermon1020191987
Forest Sta1020001978
Reeds920241990
Hudson920161975
Northfield819811976
Carrying Pl820241979
Clayton Lake820081977
Ludlow819951968
Seboomook Lk720141974
Pillsbury Pd719681968
Weeks Brook620161995
Topsfield619961978
Bethel520191977
Telos520061995
Brownfield520092009
Clayton Lake 2520112010
Stacyville520242021
Wilson Mills420241983
Manchester419951973
Aurora420211975
Heron Lake420031983

Black-throated Blue Warbler Population Trend in Other States

connecticutgeorgiamarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinapennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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