BirdAnalyst
Species · New Hampshire · BBS 2026 Release · 1966–2025

Common Grackle Population Trend in New Hampshire

All statesGeneralists

Common Grackle in New Hampshire has fallen sharply: down 53% on the route-weighted index since 1968.

-53%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 New HampshireNotable 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 New Hampshire: down 53% on the route-weighted index since 1968.

Common Grackle Population Forecast in New Hampshire

If the recent trend holds, Common Grackle in New Hampshire is projected to fall about 45% by 2030 — from 4.9 in 2025 to a central estimate of 2.7 (95% range 0.00–6.6). A 5-year backtest shows a typical error of ±37.9%, with 80% of held-out values landing inside the 95% band.

-45%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 →
2.7Projected 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 →
0.00–6.695% 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 →
±37.9%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 New Hampshire is projected to fall about 45% by 2030 — from 4.9 in 2025 to a central estimate of 2.7 (95% range 0.00–6.6). A 5-year backtest shows a typical error of ±37.9%, with 80% 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 →
20263.60.007.5
20273.30.007.3
20283.10.007.0
20292.90.006.8
20302.70.006.6

Common Grackle Survey Routes in New Hampshire

Routes recording Common Grackle in New Hampshire.
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 →
Marlow1220251966
Franconia1220251966
Concord1120251966
Walpole1020251966
Milan1020251966
Wilmot820251966
Dixvil Notch820171967
Dixville Notch 2820252018
Epsom620251966
Lempster620251966
Brentwood419981966
Fitzwilliam420251966
Dover420251966
East Kingston420251999
Strafford320251966
Canterbury320251966
Mt Chocorua320251966
Jefferson Hl320251966
Glen320241975
Peterborough220251966
Crawford Not219751966
Hopkinton120251966
Gilmantn I W120221969
Stratford120251966
Clarksville120251966

Common Grackle Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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