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

Common Grackle Population Trend in Delaware

All statesGeneralists

Common Grackle in Delaware has fallen sharply: down 54% on the route-weighted index since 1968.

-54%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 →
17Routes 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 DelawareNotable 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 Delaware: down 54% on the route-weighted index since 1968.

Common Grackle Population Forecast in Delaware

If the recent trend holds, Common Grackle in Delaware is projected to rise about 42% by 2029 — from 84 in 2024 to a central estimate of 120 (95% range 12–228). A 5-year backtest shows a typical error of ±132.7%, with 100% of held-out values landing inside the 95% band.

+42%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 →
120Projected 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 →
12–22895% 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 →
±132.7%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 Delaware is projected to rise about 42% by 2029 — from 84 in 2024 to a central estimate of 120 (95% range 12–228). A 5-year backtest shows a typical error of ±132.7%, 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 →
202512618234
202612517233
202712315231
202812214230
202912012228

Common Grackle Survey Routes in Delaware

Routes recording Common Grackle in Delaware.
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 →
Lowes Xrds23819911966
Holleyville20420041966
Dover20019871966
Frankford16420121966
Milton 214920172017
Millsboro13920242017
Harrington12620241966
Milton12420161966
Bethany Bch6719901966
Holleyville 26520242006
Frederica6120141966
Pepperbox5820161998
Pepperbox 25220242017
Blackbird4020241994
Mt Pleasant3920191966
Wilmington3320141966
Georgetown2920221992

Common Grackle Population Trend in Other States

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

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.