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Species · Delaware · BBS 2025 Release · 1966–2024

Ring-billed Gull Population Trend in Delaware

All statesWetland birds

Ring-billed Gull in Delaware has fallen sharply: down 66% on the route-weighted index since 1968.

-66%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 →
12Routes 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 →
42YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Ring-billed Gull 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 →

Ring-billed Gull has fallen sharply in Delaware: down 66% on the route-weighted index since 1968.

Ring-billed Gull Population Forecast in Delaware

If the recent trend holds, Ring-billed Gull in Delaware is projected to rise about 394% by 2024 — from 0.43 in 2019 to a central estimate of 2.1 (95% range 0.00–14). A 5-year backtest shows a typical error of ±225%, with 100% of held-out values landing inside the 95% band.

+394%Change by 2024TrendPercent 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 →
2.1Projected 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1495% 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 →
±225%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, Ring-billed Gull in Delaware is projected to rise about 394% by 2024 — from 0.43 in 2019 to a central estimate of 2.1 (95% range 0.00–14). A 5-year backtest shows a typical error of ±225%, with 100% of held-out values landing inside the 95% band.19662024
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 →
20202.20.0014
20212.20.0014
20222.20.0014
20232.10.0014
20242.10.0014

Ring-billed Gull Survey Routes in Delaware

Routes recording Ring-billed Gull 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 →
Blackbird2520172006
Bethany Bch2019671966
Harrington520141966
Frederica520131967
Lowes Xrds419911967
Dover319871969
Millsboro320192019
Mt Pleasant120071967
Wilmington120141986
Holleyville119911991
Milton120141969
Holleyville 2120082008

Ring-billed Gull Population Trend in Other States

alabamaarizonacaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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