BirdAnalyst
Species · Connecticut · BBS 2026 Release · 1966–2025

Yellow Warbler Population Trend in Connecticut

All statesForest birds

Yellow Warbler in Connecticut has surged: up 161% on the route-weighted index since 1968.

+161%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 →
59YearsYears 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 161% 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 stay roughly flat through 2030, near 13 (95% range 5.4–21). A 5-year backtest shows a typical error of ±76%, with 80% of held-out values landing inside the 95% band.

-4%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 →
13Projected 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 →
5.4–2195% 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 →
±76%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 stay roughly flat through 2030, near 13 (95% range 5.4–21). A 5-year backtest shows a typical error of ±76%, with 80% 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 →
2026135.121
2027135.221
2028135.221
2029135.321
2030135.421

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
Uncasville3420251973
Woodstock 22720252016
Willimantic2620181967
Warren 22420252012
Sherman1620191972
New Hartford1419871972
Long Hill1020191972
Granby920251988
Mid Haddam820251973
E Hartland719921966
No Woodbury720251967
Buckingham620221967
Southington320251973
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 2026-08-14.