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

Common Grackle Population Trend in Vermont

All statesGeneralists

Common Grackle in Vermont has fallen sharply: down 63% on the route-weighted index since 1968.

-63%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 →
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 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 63% 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 37% by 2029 — from 7.8 in 2024 to a central estimate of 4.9 (95% range 0.00–15). A 5-year backtest shows a typical error of ±31.3%, with 100% of held-out values landing inside the 95% band.

-37%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 →
4.9Projected 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 →
0.00–1595% 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 →
±31.3%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 Vermont is projected to fall about 37% by 2029 — from 7.8 in 2024 to a central estimate of 4.9 (95% range 0.00–15). A 5-year backtest shows a typical error of ±31.3%, 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 →
20256.20.0016
20265.90.0016
20275.50.0015
20285.20.0015
20294.90.0015

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
Shaftsbury1920241966
East Haven1820241966
Greensboro1820241967
Hinesburg1819941966
Landgrove1420241966
Grand Isle1120241967
Colchester820241986
S Wallingfrd620221966
East Calais620241966
S Reading520241966
W Rutland520241966
Fletcher520241968
Middlesex420241968
Northfld Fls320211980
Newbury 2320232005
Bristol320181995
Stratton220231966
St Johnsbury220231970
Newbury220041986
Stowe220241988
Marlboro120231966
North Pownal120241966
Gaysville120211966

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 2026-05-22.