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Species · Maine · BBS 2026 Release · 1966–2025

Great Black-backed Gull Population Trend in Maine

All statesWetland birds

Great Black-backed Gull in Maine has declined: down 44% on the route-weighted index since 1968.

-44%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 →
17Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Great Black-backed Gull Trends in MaineNotable 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 in Maine. See the full index history below.

Great Black-backed Gull Population Forecast in Maine

If the recent trend holds, Great Black-backed Gull in Maine is projected to rise about 263% by 2030 — from 0.11 in 2025 to a central estimate of 0.40 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±65%, with 80% of held-out values landing inside the 95% band.

+263%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 →
0.40Projected 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 →
0.00–1.695% 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 →
±65%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 in Maine is projected to rise about 263% by 2030 — from 0.11 in 2025 to a central estimate of 0.40 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±65%, with 80% of held-out values landing inside the 95% band.19662030
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 →
20260.420.001.6
20270.420.001.6
20280.410.001.6
20290.410.001.6
20300.400.001.6

Great Black-backed Gull Survey Routes in Maine

Routes recording Great Black-backed Gull in Maine.
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 →
Hartford719881975
Newcastle420071971
Medway319791976
Biddeford219751973
Kittery Pt220251966
Deblois219981969
Cape Neddick119931975
Westbrook119881977
Turner119961996
Warren119851973
Brooks119931984
St David120052004
Jefferson119961996
Hancock119871969
Castine120001982
Cooper120071977
Moose River119871986

Great Black-backed Gull Population Trend in Other States

connecticutdelawaremarylandmassachusettsnew-hampshirenew-jerseynew-yorknorth-carolinaohiorhode-islandvermontvirginia

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.