BirdAnalyst
Species · BBS 2025 Release · 1966–2024

California Gull

LaridaeWetland birdsLarus californicus

California Gull has surged: up 360% on the route-weighted index since 1970.

+360%Since 1970TrendPercent 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 →
325RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the California Gull

The California Gull (Larus californicus) is a North American member of the Gulls, Terns & Skimmers (Laridae). In this analysis it is grouped with the wetland birds.

Size
8.5–31.5 in long (22–80 cm) — a long-winged waterbird (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 325 Breeding Bird Survey routes across 14 states, most concentrated in the Great Basin.
Family
Laridae · Wetland birds

Notable California Gull TrendsNotable 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 increasecomputed 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 surged in surveyed states: up 360% on the route-weighted index since 1970.

California Gull Population Forecast

If the recent trend holds, California Gull is projected to rise about 18% by 2029 — from 1.4 in 2024 to a central estimate of 1.6 (95% range 0.89–2.4). A 5-year backtest shows a typical error of ±44.7%, with 80% of held-out values landing inside the 95% band.

+18%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 →
1.6Projected 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 →
0.89–2.495% 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 →
±44.7%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 is projected to rise about 18% by 2029 — from 1.4 in 2024 to a central estimate of 1.6 (95% range 0.89–2.4). A 5-year backtest shows a typical error of ±44.7%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20251.60.822.3
20261.60.842.4
20271.60.852.4
20281.60.872.4
20291.60.892.4

Where the California Gull Is Detected

BBS routes recording California Gull, sized by most recent count.

California Gull Population Trend by State

California Gull population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alaskainsufficient datan/a3
California+26%197358
Colorado148×198615
Idaho-94%197126
Minnesotainsufficient datan/a1
Montana-51%197043
Nevada+8%197312
New Mexicoinsufficient datan/a1
North Dakota+59%197621
Oregon+201%197127
South Dakota-34%20043
Utah+299%197034
Washington+61%198035
Wyoming-11%197046

California Gull Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

California Gull population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest+66%197225
Great Basin+7%1970109
Northern Rockies+71%197062
Prairie Potholes+312%197139
Sierra Nevada-98%197410
Southern Rockies / Colorado Plateau15×197426
Badlands and Prairies-49%197124
Shortgrass Prairie13×19866
Coastal California74×197321
Sonoran and Mojave Deserts-96%19933

California Gull Conservation Status

Our route-weighted index shows it up about 360% since 1970.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.