BirdAnalyst
Species · Maine · BBS 2025 Release · 1966–2024

Herring Gull Population Trend in Maine

All statesWetland birds

Herring Gull in Maine has collapsed: down 88% on the route-weighted index since 1968.

-88%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 →
41Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Herring 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 →

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 →

Herring Gull has collapsed in Maine: down 88% on the route-weighted index since 1968.

Herring Gull Population Forecast in Maine

If the recent trend holds, Herring Gull in Maine is projected to fall about 100% by 2029 — from 1.8 in 2024 to a central estimate of 0.00 (95% range 0.00–8.0). A 5-year backtest shows a typical error of ±227.1%, with 80% 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 →
0.00–8.095% 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 →
±227.1%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 Maine is projected to fall about 100% by 2029 — from 1.8 in 2024 to a central estimate of 0.00 (95% range 0.00–8.0). A 5-year backtest shows a typical error of ±227.1%, with 80% 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 →
20250.000.008.0
20260.000.008.0
20270.000.008.0
20280.000.008.0
20290.000.008.0

Herring Gull Survey Routes in Maine

Routes recording Herring 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 →
Kittery Pt3120241966
Moose River2820081983
Biddeford820061973
Jefferson820101992
Deblois520071966
Greenville419991977
Seboomook Lk320141972
Newcastle220241971
Bethel219891979
Turner220101972
Hartford219821975
Brooks220161977
Hancock220111969
Cooper220051975
Cape Neddick120231972
Westbrook120101977
Wilson Mills120241984
Greenwood119991974
South Arm119791979
Otisfield Gr120121966
Bowdoin Ctr119991971
Manchester119801971
East Troy119961972
Warren119901973
Freedom119921978

Herring Gull Population Trend in Other States

alabamaalaskacaliforniacoloradoconnecticutdelawarefloridaidahoillinoisindianakansaslouisianamarylandmassachusettsmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-carolinatexasvermontvirginiawashingtonwest-virginiawisconsin

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