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

Common Grackle Population Trend in Vermont

All statesGeneralists

Common Grackle in Vermont has fallen sharply: down 58% on the route-weighted index since 1968.

-58%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 →
26Routes 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 VermontNotable 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 Vermont: down 58% on the route-weighted index since 1968.

Common Grackle Population Forecast in Vermont

If the recent trend holds, Common Grackle in Vermont is projected to fall about 44% by 2030 — from 8.4 in 2025 to a central estimate of 4.7 (95% range 0.00–14). A 5-year backtest shows a typical error of ±19.9%, with 100% of held-out values landing inside the 95% band.

-44%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 →
4.7Projected 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 →
0.00–1495% 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 →
±19.9%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 Vermont is projected to fall about 44% by 2030 — from 8.4 in 2025 to a central estimate of 4.7 (95% range 0.00–14). A 5-year backtest shows a typical error of ±19.9%, 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 →
20266.00.0016
20275.70.0015
20285.40.0015
20295.00.0015
20304.70.0014

Common Grackle Survey Routes in Vermont

Routes recording Common Grackle in Vermont.
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 →
Waterville3019801967
Hardwick2320241966
Fletcher2120251968
East Haven1920251966
Hinesburg1819941966
Landgrove1620251966
Gaysville1620251966
Greensboro1420251967
Grand Isle1120241967
W Rutland1020251966
Middlesex1020251968
North Pownal920251966
St Johnsbury920251970
Shaftsbury820251966
Post Mills720251966
East Calais720251966
S Wallingfrd620221966
S Reading520241966
Northfld Fls320211980
Newbury 2320232005
Stratton220251966
Newbury220041986
Colchester220251986
Stowe220241988
Bristol220251995

Common Grackle Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvirginiawest-virginiawisconsinwyoming

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