BirdAnalyst
Species · BCR 4 · BBS 2025 Release · 1966–2024

Glaucous-winged Gull In BCR 4

All regionsBCR 4Wetland birds

Glaucous-winged Gull in BCR 4 has collapsed: down 99% on the route-weighted index since 1982.

-99%Since 1982TrendPercent 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 →
19Routes 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 →
39YearsYears 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 declinecomputed 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 collapsed in BCR 4: down 99% on the route-weighted index since 1982.

Glaucous-winged Gull In BCR 4 Population Forecast

If the recent trend holds, Glaucous-winged Gull in BCR 4 is projected to fall about 100% by 2029 — from 0.14 in 2024 to a central estimate of 0.00 (95% range 0.00–24). A 5-year backtest shows a typical error of ±4600.8%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–2495% 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 →
±4600.8%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 in BCR 4 is projected to fall about 100% by 2029 — from 0.14 in 2024 to a central estimate of 0.00 (95% range 0.00–24). A 5-year backtest shows a typical error of ±4600.8%, with 100% of held-out values landing inside the 95% band.19772029
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 →
20250.000.0024
20260.000.0024
20270.000.0024
20280.000.0024
20290.000.0024

Routes In BCR 4

Routes recording Glaucous-winged Gull in BCR 4.
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 →
HomerALASKA4631982
KalifonskyALASKA302023
PetersvilleALASKA61987
CohoeALASKA52016
CottonwoodALASKA31990
Hatcher PassALASKA21999
Burma RoadALASKA22006
Unalakleet RiverALASKA22024
KuskulanaALASKA21990
WillowALASKA12021
Swan Lake RdALASKA12012
Anchor RiverALASKA12023
Seven LakesALASKA12018
KachemakALASKA12022
Hather CreekALASKA12024
Kanuti CanynALASKA12016
McgrathALASKA11999
Mud RiverALASKA12024
Anvik RiverALASKA12024

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