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Species · Washington · BBS 2025 Release · 1966–2024

California Gull Population Trend in Washington

All statesWetland birds

California Gull in Washington has risen sharply: up 61% on the route-weighted index since 1980.

+61%Since 1980TrendPercent 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 →
35Routes 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 →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable California Gull Trends in WashingtonNotable 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 risen sharply in Washington: up 61% on the route-weighted index since 1980.

California Gull Population Forecast in Washington

If the recent trend holds, California Gull in Washington is projected to rise about 95% by 2029 — from 0.93 in 2024 to a central estimate of 1.8 (95% range 0.00–7.3). A 5-year backtest shows a typical error of ±63.4%, with 100% of held-out values landing inside the 95% band.

+95%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 →
1.8Projected 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 →
0.00–7.395% 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 →
±63.4%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 Washington is projected to rise about 95% by 2029 — from 0.93 in 2024 to a central estimate of 1.8 (95% range 0.00–7.3). A 5-year backtest shows a typical error of ±63.4%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20251.70.007.2
20261.80.007.3
20271.80.007.3
20281.80.007.3
20291.80.007.3

California Gull Survey Routes in Washington

Routes recording California Gull in Washington.
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 →
Taholah90020081999
Potholes7120191996
Mercer4919851977
Keystone4820241994
Ozette3819951995
Warm Beach 23220182018
Ronald2919901990
Moses Lake1620221992
Nighthawk1419961992
Cougar919911972
Columbia Nwr720221992
Quincy720211988
Ewan519861986
Mendota519801980
Ellensburg520191986
Scootney Reservoir520242009
Raymond520192013
Rimrock420181984
Tonasket420072007
Othello319871981
Hanford Site219961989
Brewster219981998
Turnbull Nwr219931993
Wapato219931983
Horn Rapids220122005

California Gull Population Trend in Other States

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