BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Glaucous-winged Gull Population Analysis

LaridaeWetland birdsLarus glaucescens

Glaucous-winged Gull has surged: up 112% on the route-weighted index since 1970.

+112%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 →
93RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years 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 Glaucous-winged Gull

The Glaucous-winged Gull (Larus glaucescens) 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 93 Breeding Bird Survey routes across 4 states, most concentrated in the Northern Pacific Rainforest.
Family
Laridae · Wetland birds

Notable Glaucous-winged 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 →

Glaucous-winged Gull has surged in surveyed states: up 112% on the route-weighted index since 1970.

Glaucous-winged Gull Population Forecast

If the recent trend holds, Glaucous-winged Gull is projected to rise about 112% by 2030 — from 0.08 in 2025 to a central estimate of 0.18 (95% range 0.00–0.44). A 5-year backtest shows a typical error of ±135%, with 100% of held-out values landing inside the 95% band.

+112%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 →
0.18Projected 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 →
0.00–0.4495% 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 →
±135%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, Glaucous-winged Gull is projected to rise about 112% by 2030 — from 0.08 in 2025 to a central estimate of 0.18 (95% range 0.00–0.44). A 5-year backtest shows a typical error of ±135%, 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 →
20260.180.000.45
20270.180.000.45
20280.180.000.45
20290.180.000.44
20300.180.000.44

Where the Glaucous-winged Gull Is Detected

BBS routes recording Glaucous-winged Gull, sized by most recent count.

Glaucous-winged Gull Population Trend by State

Glaucous-winged 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 →
Alaska+262%197460
California-26%19768
Oregon-18%19735
Washington-71%197020

Glaucous-winged Gull Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Glaucous-winged 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 →
BCR 2-66%198517
BCR 4-99%198219
Northern Pacific Rainforest-54%197053

Glaucous-winged Gull Conservation Status

Our route-weighted index shows it up about 112% since 1970.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.