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

Ring-billed Gull Population Trend in California

All statesWetland birds

Ring-billed Gull in California has held roughly steady: up 8% on the route-weighted index since 1973.

+8%Since 1973TrendPercent 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 →
46Routes 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 →
51YearsYears 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 CaliforniaNotable 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 Ring-billed Gull in California. See the full index history below.

Ring-billed Gull Population Forecast in California

If the recent trend holds, Ring-billed Gull in California is projected to rise about 167% by 2029 — from 2.5 in 2024 to a central estimate of 6.6 (95% range 0.00–17). A 5-year backtest shows a typical error of ±16515.2%, with 100% of held-out values landing inside the 95% band.

+167%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 →
6.6Projected 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 →
0.00–1795% 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 →
±16515.2%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 California is projected to rise about 167% by 2029 — from 2.5 in 2024 to a central estimate of 6.6 (95% range 0.00–17). A 5-year backtest shows a typical error of ±16515.2%, with 100% of held-out values landing inside the 95% band.19712029
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 →
20256.60.0017
20266.60.0017
20276.60.0017
20286.60.0017
20296.60.0017

Ring-billed Gull Survey Routes in California

Routes recording Ring-billed Gull in California.
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 →
Dorris27620191972
Likely23020241971
Sattley12720121974
Livermore5019911991
Brawley4320091974
Macdoel3520191972
Nubieber2620071980
Poway2619801973
Honey Lake1720191973
Ingalls1620011973
Fairfax1519891973
Iron Gate1020191988
Chilcoot1020081998
Lakeshore819991999
Glenn720051978
Mt Shasta720021978
Crowder Flat620192002
Collegeville519791979
Genesee419821974
Riovista320172017
Hughson320081981
Davis Creek320101972
Orleans219801980
Clear Lk Res220181972
Last Chance220092006

Ring-billed Gull Population Trend in Other States

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

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