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Species · Delaware · BBS 2026 Release · 1966–2025

Boat-tailed Grackle Population Trend in Delaware

All statesWetland birds

Boat-tailed Grackle in Delaware has held roughly steady: down 2% on the route-weighted index since 1968.

-2%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 →
9Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Boat-tailed 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 →

No notable trend signals for Boat-tailed Grackle in Delaware. See the full index history below.

Boat-tailed Grackle Population Forecast in Delaware

If the recent trend holds, Boat-tailed Grackle in Delaware is projected to rise about 41% by 2030 — from 1.3 in 2025 to a central estimate of 1.9 (95% range 0.00–8.2). A 5-year backtest shows a typical error of ±43.1%, with 100% of held-out values landing inside the 95% band.

+41%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 →
1.9Projected 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 →
0.00–8.295% 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 →
±43.1%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, Boat-tailed Grackle in Delaware is projected to rise about 41% by 2030 — from 1.3 in 2025 to a central estimate of 1.9 (95% range 0.00–8.2). A 5-year backtest shows a typical error of ±43.1%, 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 →
20262.00.008.3
20272.00.008.3
20281.90.008.2
20291.90.008.2
20301.90.008.2

Boat-tailed Grackle Survey Routes in Delaware

Routes recording Boat-tailed 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 →
Bethany Bch6419901966
Holleyville 21020092006
Lowes Xrds919861968
Harrington820251967
Blackbird820151994
Milton419711971
Georgetown420211995
Dover219791974
Pepperbox120041999

Boat-tailed Grackle Population Trend in Other States

alabamafloridageorgialouisianamarylandmississippinew-jerseynew-yorknorth-carolinasouth-carolinatexasvirginia

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