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

Common Grackle Population Trend in Connecticut

All statesGeneralists

Common Grackle in Connecticut has fallen sharply: down 71% on the route-weighted index since 1968.

-71%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 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 71% 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 24% by 2029 — from 14 in 2024 to a central estimate of 11 (95% range 0.00–23). A 5-year backtest shows a typical error of ±25.2%, with 100% of held-out values landing inside the 95% band.

-24%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 →
11Projected 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 →
0.00–2395% 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 →
±25.2%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 24% by 2029 — from 14 in 2024 to a central estimate of 11 (95% range 0.00–23). A 5-year backtest shows a typical error of ±25.2%, with 100% 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 →
2025120.1425
2026120.0024
2027110.0024
2028110.0023
2029110.0023

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
Southington2920241973
E Hartland2819921966
Warren2620111972
Westbrook2220241969
New Hartford1819871972
Sherman1720191972
Greenwich1620181967
Mid Haddam1620241973
New Hartford1620241994
Uncasville1520241973
Willimantic1320181967
Mystic1120231973
Danbury1120231968
Granby1120241988
Woodstock 2720242016
Woodstock620071968
Buckingham420221966
No Woodbury420241967
Warren 2420242012

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 2026-05-22.