BirdAnalyst
Species · Connecticut · BBS 2025 Release · 1966–2024

Yellow Warbler Population Trend in Connecticut

All statesForest birds

Yellow Warbler in Connecticut has surged: up 103% on the route-weighted index since 1968.

+103%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 Yellow 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 →

Yellow Warbler has surged in Connecticut: up 103% on the route-weighted index since 1968.

Yellow Warbler Population Forecast in Connecticut

If the recent trend holds, Yellow Warbler in Connecticut is projected to rise about 28% by 2029 — from 10 in 2024 to a central estimate of 13 (95% range 5.2–21). A 5-year backtest shows a typical error of ±90.7%, with 60% of held-out values landing inside the 95% band.

+28%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 →
13Projected 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 →
5.2–2195% 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 →
±90.7%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, Yellow Warbler in Connecticut is projected to rise about 28% by 2029 — from 10 in 2024 to a central estimate of 13 (95% range 5.2–21). A 5-year backtest shows a typical error of ±90.7%, with 60% 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 →
2025134.921
2026134.921
2027135.021
2028135.121
2029135.221

Yellow Warbler Survey Routes in Connecticut

Routes recording Yellow 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 →
Warren7220111972
Woodstock3520071968
Willimantic2620181967
Woodstock 22520242016
Uncasville2320241973
Sherman1620191972
New Hartford1419871972
Mid Haddam1220241973
Long Hill1020191972
Warren 21020242012
No Woodbury920241967
Granby820241988
E Hartland719921966
Buckingham620221967
Southington320241973
Westbrook220241969
Mystic120231973
Greenwich120181967
Danbury120231968
New Hartford120241994

Yellow Warbler Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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