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

Herring Gull In BCR 4

All regionsBCR 4Wetland birds

Herring Gull in BCR 4 has risen sharply: up 53% on the route-weighted index since 1976.

+53%Since 1976TrendPercent 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 →
43Routes 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 →
45YearsYears 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 →

Herring Gull has risen sharply in BCR 4: up 53% on the route-weighted index since 1976.

Forecast

If the recent trend holds, Herring Gull in BCR 4 is projected to rise about 367% by 2029 — from 0.94 in 2024 to a central estimate of 4.4 (95% range 0.00–13). A 5-year backtest shows a typical error of ±224.9%, with 80% of held-out values landing inside the 95% band.

+367%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 →
4.4Projected 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 →
0.00–1395% 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 →
±224.9%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, Herring Gull in BCR 4 is projected to rise about 367% by 2029 — from 0.94 in 2024 to a central estimate of 4.4 (95% range 0.00–13). A 5-year backtest shows a typical error of ±224.9%, 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 →
20254.20.0012
20264.20.0012
20274.30.0012
20284.40.0013
20294.40.0013

Routes In BCR 4

Routes recording Herring 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 →
KalifonskyALASKA3222023
CohoeALASKA212023
ChistochinaALASKA132024
TonsinaALASKA62016
Nicholai SlALASKA62018
Kenny LakeALASKA52024
Porcupine R.ALASKA52002
Seven LakesALASKA42023
DeltaALASKA42024
KuskulanaALASKA42024
NorthwayALASKA32022
Goose BayALASKA31982
Lake LouiseALASKA32012
KachemakALASKA32024
Unalakleet RiverALASKA31999
MaclarenALASKA22024
MonahanALASKA22021
SavageALASKA22016
WasillaALASKA21983
McgrathALASKA22019
TatalinaALASKA22012
Kanuti LakeALASKA22022
Birch LakeALASKA12024
SlanaALASKA12024
CantwellALASKA11982

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