BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Great Black-backed Gull

LaridaeWetland birdsLarus marinus

Great Black-backed Gull has held roughly steady: down 5% on the route-weighted index since 1968.

-5%Since 1968TrendPercent 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 →
82RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years 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 Great Black-backed Gull

The Great Black-backed Gull (Larus marinus) 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 82 Breeding Bird Survey routes across 13 states, most concentrated in the New England / Mid-Atlantic Coast.
Family
Laridae · Wetland birds

Notable Great Black-backed 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 →

No notable trend signals for Great Black-backed Gull. See the full index history below.

Great Black-backed Gull Population Forecast

If the recent trend holds, Great Black-backed Gull is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.06). A 5-year backtest shows a typical error of ±239.8%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.03Projected 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 →
0.00–0.0695% 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 →
±239.8%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, Great Black-backed Gull is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.06). A 5-year backtest shows a typical error of ±239.8%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.030.000.06
20260.030.000.06
20270.030.000.06
20280.030.000.06
20290.030.000.06

Where the Great Black-backed Gull Is Detected

BBS routes recording Great Black-backed Gull, sized by most recent count.

Great Black-backed Gull Population Trend by State

Great Black-backed 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 →
Connecticut+7%19763
Delaware-67%19688
Maine+111%196817
Maryland+6%197511
Massachusetts-62%197012
New Hampshire-81%19695
New Jersey+580%19845
New York+203%19727
North Carolina-88%19825
Ohioinsufficient datan/a1
Rhode Island+324%19713
Vermontinsufficient datan/a1
Virginia-11%19964

Great Black-backed Gull Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Great Black-backed 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 →
Atlantic Northern Forest-59%197116
Southeastern Coastal Plain-75%19825
New England / Mid-Atlantic Coast+137%196855

Great Black-backed Gull Conservation Status

Our route-weighted index shows it down about 5% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.