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Species · Connecticut · BBS 2025 Release · 1966–2024

Worm-eating Warbler Population Trend in Connecticut

All statesForest birds

Worm-eating Warbler in Connecticut has surged: up 568% on the route-weighted index since 1972.

+568%Since 1972TrendPercent 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 →
17Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Worm-eating 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 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 →

Worm-eating Warbler has surged in Connecticut: up 568% on the route-weighted index since 1972.

Worm-eating Warbler Population Forecast in Connecticut

If the recent trend holds, Worm-eating Warbler in Connecticut is projected to fall about 40% by 2029 — from 1.4 in 2024 to a central estimate of 0.87 (95% range 0.39–1.4). A 5-year backtest shows a typical error of ±43.1%, with 60% of held-out values landing inside the 95% band.

-40%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 →
0.87Projected 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 →
0.39–1.495% 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 →
±43.1%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, Worm-eating Warbler in Connecticut is projected to fall about 40% by 2029 — from 1.4 in 2024 to a central estimate of 0.87 (95% range 0.39–1.4). A 5-year backtest shows a typical error of ±43.1%, with 60% of held-out values landing inside the 95% band.19672029
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 →
20250.830.341.3
20260.840.351.3
20270.850.371.3
20280.860.381.3
20290.870.391.4

Worm-eating Warbler Survey Routes in Connecticut

Routes recording Worm-eating 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 →
Uncasville720241977
Willimantic520181993
Westbrook320241978
Mystic220141979
Danbury220231969
Long Hill220191974
Woodstock 2220242024
Buckingham120141978
Woodstock120071972
No Woodbury120242022
Sherman120191978
Greenwich120001967
Warren120052001
Mid Haddam120231975
New Hartford120052005
New Hartford119841984
Granby119891989

Worm-eating Warbler Population Trend in Other States

alabamaarkansasdelawaregeorgiaillinoisindianaiowakentuckylouisianamarylandmassachusettsmississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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