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Species · Connecticut · BBS 2025 Release · 1966–2024

Blue-winged Warbler Population Trend in Connecticut

All statesForest birds

Blue-winged Warbler in Connecticut has collapsed: down 76% on the route-weighted index since 1968.

-76%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 →
20Routes 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 Blue-winged 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 →

long arc declinecomputed 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 →

Blue-winged Warbler has collapsed in Connecticut: down 76% on the route-weighted index since 1968.

Blue-winged Warbler Population Forecast in Connecticut

If the recent trend holds, Blue-winged Warbler in Connecticut is projected to fall about 29% by 2029 — from 0.56 in 2024 to a central estimate of 0.40 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±23.6%, with 100% of held-out values landing inside the 95% band.

-29%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 →
0.40Projected 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 →
0.00–2.595% 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 →
±23.6%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, Blue-winged Warbler in Connecticut is projected to fall about 29% by 2029 — from 0.56 in 2024 to a central estimate of 0.40 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±23.6%, 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 →
20250.700.002.8
20260.630.002.8
20270.550.002.7
20280.470.002.6
20290.400.002.5

Blue-winged Warbler Survey Routes in Connecticut

Routes recording Blue-winged 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 →
Willimantic620181967
Uncasville220241973
Westbrook220061972
Danbury220151968
Warren220111972
New Hartford219871972
Woodstock 2220242016
Granby220191988
Mystic120231973
E Hartland119921966
Buckingham120211966
Woodstock120071968
No Woodbury120241967
Sherman120191973
Greenwich119991967
Long Hill120191973
Mid Haddam120191973
Southington120061973
New Hartford120061994
Warren 2120182012

Blue-winged Warbler Population Trend in Other States

alabamaarkansasdelawaregeorgiaillinoisindianaiowakentuckymarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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