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Species · Connecticut · BBS 2025 Release · 1966–2024

Black-throated Green Warbler Population Trend in Connecticut

All statesForest birds

Black-throated Green Warbler in Connecticut has declined: down 29% on the route-weighted index since 1971.

-29%Since 1971TrendPercent 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 →
18Routes 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 →
54YearsYears 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 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 Green Warbler in Connecticut. See the full index history below.

Black-throated Green Warbler Population Forecast in Connecticut

If the recent trend holds, Black-throated Green Warbler in Connecticut is projected to rise about 143% by 2029 — from 0.33 in 2024 to a central estimate of 0.81 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±225.8%, with 100% of held-out values landing inside the 95% band.

+143%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 →
0.81Projected 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 →
0.00–1.795% 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 →
±225.8%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 Green Warbler in Connecticut is projected to rise about 143% by 2029 — from 0.33 in 2024 to a central estimate of 0.81 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±225.8%, 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 →
20250.780.001.6
20260.790.001.6
20270.790.001.7
20280.800.001.7
20290.810.001.7

Black-throated Green Warbler Survey Routes in Connecticut

Routes recording Black-throated Green 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 →
Warren1920111972
Mystic220041977
Sherman220101981
E Hartland119661966
Buckingham119841970
Uncasville120231979
Woodstock120071970
Westbrook119981985
Willimantic120171975
No Woodbury120231981
Greenwich119721972
New Hartford120241994
Long Hill120191979
Mid Haddam120051976
Southington120102007
Woodstock 2120222021
Warren 2120242012
Granby120241992

Black-throated Green Warbler Population Trend in Other States

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

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