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Species · Massachusetts · BBS 2025 Release · 1966–2024

Herring Gull Population Trend in Massachusetts

All statesWetland birds

Herring Gull in Massachusetts has collapsed: down 96% on the route-weighted index since 1968.

-96%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 →
18Routes 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 MassachusettsNotable 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 Massachusetts: down 96% on the route-weighted index since 1968.

Herring Gull Population Forecast in Massachusetts

If the recent trend holds, Herring Gull in Massachusetts is projected to fall about 100% by 2029 — from 0.73 in 2024 to a central estimate of 0.00 (95% range 0.00–25). A 5-year backtest shows a typical error of ±1702.6%, 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 →
0.00–2595% 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 →
±1702.6%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 Massachusetts is projected to fall about 100% by 2029 — from 0.73 in 2024 to a central estimate of 0.00 (95% range 0.00–25). A 5-year backtest shows a typical error of ±1702.6%, 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 →
20250.000.0025
20260.000.0025
20270.000.0025
20280.000.0025
20290.000.0025

Herring Gull Survey Routes in Massachusetts

Routes recording Herring Gull in Massachusetts.
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 →
Chilmark34019831969
Newburyport1720221967
Gay Head1120241996
Cape Cod Ns720071989
E Dennis520211967
Wellfleet 2520212016
Wellfleet420051966
Marion220221966
S Barre219731970
N. Andover220051995
Prattville120021966
Brockton120191967
Maynard119771967
Littleton120051967
Mansfield120161987
E Pepperell119941967
Holden119801980
Ware River119951995

Herring Gull Population Trend in Other States

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

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