BirdAnalyst
Species · BCR 33 · BBS 2026 Release · 1966–2025

California Gull In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsWetland birds

California Gull in Sonoran and Mojave Deserts has collapsed: down 96% on the route-weighted index since 1993.

-96%Since 1993TrendPercent 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 →
3Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
18YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

California Gull has collapsed in Sonoran and Mojave Deserts: down 96% on the route-weighted index since 1993.

California Gull In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, California Gull in Sonoran and Mojave Deserts is projected to stay roughly flat through 2030, near 0.00 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±643.5%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.00Projected 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 →
0.00–1.595% 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 →
±643.5%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, California Gull in Sonoran and Mojave Deserts is projected to stay roughly flat through 2030, near 0.00 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±643.5%, with 100% of held-out values landing inside the 95% band.19762030
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 →
20260.000.001.5
20270.000.001.5
20280.000.001.5
20290.000.001.5
20300.000.001.5

Routes In Sonoran and Mojave Deserts

Routes recording California Gull in Sonoran and Mojave Deserts.
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 →
Haiwee ResCALIFORNIA502004
Eureka ValCALIFORNIA12014
NilandCALIFORNIA12025

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