BirdAnalyst
Species · BCR 9 · BBS 2026 Release · 1966–2025

California Gull In Great Basin

All regionsGreat BasinWetland birds

California Gull in Great Basin has declined: down 28% on the route-weighted index since 1970.

-28%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 →
111Routes 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 →
57YearsYears 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 →

No notable trend signals for California Gull in Great Basin. See the full index history below.

California Gull In Great Basin Population Forecast

If the recent trend holds, California Gull in Great Basin is projected to rise about 233% by 2030 — from 2.3 in 2025 to a central estimate of 7.6 (95% range 0.00–18). A 5-year backtest shows a typical error of ±98.6%, with 100% of held-out values landing inside the 95% band.

+233%Change 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 →
7.6Projected 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 →
0.00–1895% 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 →
±98.6%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 Great Basin is projected to rise about 233% by 2030 — from 2.3 in 2025 to a central estimate of 7.6 (95% range 0.00–18). A 5-year backtest shows a typical error of ±98.6%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20268.10.0018
20278.00.0018
20287.90.0018
20297.70.0018
20307.60.0018

Routes In Great Basin

Routes recording California Gull in Great Basin.
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 →
Johnson CanUTAH5982021
MerrillOREGON2502022
BridgeportCALIFORNIA2451977
Bear RiverUTAH1932025
HenryIDAHO1231983
Ruby Valley 2NEVADA1182024
Iron GateCALIFORNIA932019
Pine CreekUTAH901999
PotholesWASHINGTON712019
SpringfieldIDAHO652018
Sand PassNEVADA642019
LikelyCALIFORNIA582017
Oak CityUTAH542006
MercerWASHINGTON491985
GoshenUTAH452025
CedarvilleCALIFORNIA321978
DorrisCALIFORNIA312019
PocatelloIDAHO302019
UmatillaOREGON292023
RonaldWASHINGTON291990
PrincetonOREGON251985
Blacks CreekIDAHO232015
Mud LakeIDAHO222018
Carson RiverNEVADA222005
YakimaWASHINGTON182025

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