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

Boat-tailed Grackle Population Trend in Delaware

All statesGeneralists

Boat-tailed Grackle in Delaware has edged up: up 14% on the route-weighted index since 1968.

+14%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 →
54YearsYears 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 fall about 50% by 2029 — from 4.0 in 2024 to a central estimate of 2.0 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±41.5%, with 100% of held-out values landing inside the 95% band.

-50%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 →
2.0Projected 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 →
0.00–8.395% 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 →
±41.5%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 fall about 50% by 2029 — from 4.0 in 2024 to a central estimate of 2.0 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±41.5%, 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 →
20252.10.008.5
20262.10.008.4
20272.00.008.4
20282.00.008.4
20292.00.008.3

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
Harrington2020241967
Holleyville 21020092006
Lowes Xrds919861968
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 2026-05-22.