BirdAnalyst
Species · BCR 32 · BBS 2025 Release · 1966–2024

California Gull In Coastal California

All regionsCoastal CaliforniaWetland birds

California Gull in Coastal California has surged: up 74× on the route-weighted index since 1973.

74×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 →
21Routes 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 →
44YearsYears 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 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 Coastal California: up 74× on the route-weighted index since 1973.

Forecast

If the recent trend holds, California Gull in Coastal California is projected to rise about 54× by 2029 — from 0.06 in 2024 to a central estimate of 3.4 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±850.6%, with 80% of held-out values landing inside the 95% band.

54×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 →
3.4Projected 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 →
±850.6%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 Coastal California is projected to rise about 54× by 2029 — from 0.06 in 2024 to a central estimate of 3.4 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±850.6%, 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 →
20253.10.008.0
20263.20.008.1
20273.30.008.1
20283.40.008.2
20293.40.008.3

Routes In Coastal California

Routes recording California Gull in Coastal 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 →
PowayCALIFORNIA371980
OnealsCALIFORNIA102009
San YsidroCALIFORNIA91990
WestleyCALIFORNIA82017
PenningtonCALIFORNIA61995
FairfaxCALIFORNIA62018
Carrizo PlnCALIFORNIA41978
CoyoteCALIFORNIA32024
CollegevilleCALIFORNIA21985
HughsonCALIFORNIA22012
HollisterCALIFORNIA22001
AtwaterCALIFORNIA22003
CopperopolisCALIFORNIA21993
ColmaCALIFORNIA11968
VentucopaCALIFORNIA11988
OrovilleCALIFORNIA11995
TranquillityCALIFORNIA11973
MoragaCALIFORNIA12005
Bartlett SpsCALIFORNIA11991
Ora LomaCALIFORNIA11995
Staten Is.CALIFORNIA12008

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