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

Common Grackle Population Trend in Connecticut

All statesGeneralists

Common Grackle in Connecticut has fallen sharply: down 66% on the route-weighted index since 1968.

-66%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 Common Grackle 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 →

Common Grackle has fallen sharply in Connecticut: down 66% on the route-weighted index since 1968.

Common Grackle Population Forecast in Connecticut

If the recent trend holds, Common Grackle in Connecticut is projected to fall about 30% by 2030 — from 15 in 2025 to a central estimate of 10 (95% range 0.00–22). A 5-year backtest shows a typical error of ±25.3%, with 100% of held-out values landing inside the 95% band.

-30%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 →
10Projected 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 →
0.00–2295% 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 →
±25.3%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, Common Grackle in Connecticut is projected to fall about 30% by 2030 — from 15 in 2025 to a central estimate of 10 (95% range 0.00–22). A 5-year backtest shows a typical error of ±25.3%, with 100% 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 →
2026120.0024
2027120.0024
2028110.0023
2029110.0023
2030100.0022

Common Grackle Survey Routes in Connecticut

Routes recording Common Grackle 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 →
Long Hill7420191972
Mid Haddam3220251973
E Hartland2819921966
Warren2620111972
Southington2420251973
Westbrook2220251969
New Hartford1819871972
Sherman1720191972
Uncasville1620251973
Greenwich1620181967
New Hartford1620241994
Willimantic1320181967
Mystic1120231973
Danbury1120231968
Granby920251988
Woodstock 2720252016
Woodstock620071968
Buckingham420221966
No Woodbury420251967
Warren 2320252012

Common Grackle Population Trend in Other States

alabamaarkansascoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.