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Species · Connecticut · BBS 2026 Release · 1966–2025

Black-throated Blue Warbler Population Trend in Connecticut

All statesForest birds

Black-throated Blue Warbler in Connecticut has held roughly steady: down 1% on the route-weighted index since 1969.

-1%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 →
15Routes 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 ConnecticutNotable 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 Blue Warbler in Connecticut. See the full index history below.

Black-throated Blue Warbler Population Forecast in Connecticut

If the recent trend holds, Black-throated Blue Warbler in Connecticut is projected to rise about 158% by 2030 — from 0.25 in 2025 to a central estimate of 0.65 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±120.8%, with 100% of held-out values landing inside the 95% band.

+158%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 →
0.65Projected 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 →
0.00–1.395% 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 →
±120.8%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 Connecticut is projected to rise about 158% by 2030 — from 0.25 in 2025 to a central estimate of 0.65 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±120.8%, 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 →
20260.620.001.3
20270.630.001.3
20280.630.001.3
20290.640.001.3
20300.650.001.3

Black-throated Blue Warbler Survey Routes in Connecticut

Routes recording Black-throated Blue Warbler in Connecticut.
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 →
Warren420111972
E Hartland219851966
Woodstock219941987
Sherman220191976
Mid Haddam219731973
New Hartford219851973
Warren 2220252012
Westbrook119701970
New Hartford120241994
No Woodbury120151967
Greenwich120091972
Woodstock 2120232023
Long Hill119841984
Southington120161994
Granby120231988

Black-throated Blue Warbler Population Trend in Other States

georgiamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinapennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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