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Species · Connecticut · BBS 2025 Release · 1966–2024

Eastern Bluebird Population Trend in Connecticut

All statesForest birds

Eastern Bluebird in Connecticut has surged: up 283% on the route-weighted index since 1968.

+283%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 Eastern Bluebird 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 →

Eastern Bluebird has surged in Connecticut: up 283% on the route-weighted index since 1968.

Eastern Bluebird Population Forecast in Connecticut

If the recent trend holds, Eastern Bluebird in Connecticut is projected to fall about 23% by 2029 — from 5.1 in 2024 to a central estimate of 3.9 (95% range 2.4–5.4). A 5-year backtest shows a typical error of ±36.6%, with 40% of held-out values landing inside the 95% band.

-23%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 →
3.9Projected 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 →
2.4–5.495% 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 →
±36.6%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, Eastern Bluebird in Connecticut is projected to fall about 23% by 2029 — from 5.1 in 2024 to a central estimate of 3.9 (95% range 2.4–5.4). A 5-year backtest shows a typical error of ±36.6%, with 40% 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 →
20253.72.25.2
20263.82.35.3
20273.82.35.3
20283.92.45.4
20293.92.45.4

Eastern Bluebird Survey Routes in Connecticut

Routes recording Eastern Bluebird 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 →
Southington1720241978
Buckingham820221971
Sherman820191973
Mid Haddam720241973
Mystic620231973
Westbrook620241969
Greenwich620181967
Willimantic520181967
Woodstock 2520242016
Granby420241989
Uncasville320241973
Woodstock220071974
No Woodbury220241967
Danbury220231972
E Hartland119901966
Warren120111976
Long Hill120191973
New Hartford119871972
New Hartford120242010
Warren 2120242012

Eastern Bluebird Population Trend in Other States

alabamaarizonaarkansascoloradodelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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