BirdAnalyst
Species · New Hampshire · BBS 2025 Release · 1966–2024

Herring Gull Population Trend in New Hampshire

All statesWetland birds

Herring Gull in New Hampshire has collapsed: down 100% on the route-weighted index since 1968.

-100%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 →
12Routes 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 →
50YearsYears 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 New HampshireNotable 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 New Hampshire: down 100% on the route-weighted index since 1968.

Herring Gull Population Forecast in New Hampshire

If the recent trend holds, Herring Gull in New Hampshire is projected to stay roughly flat through 2028, near 0.00 (95% range 0.00–11). A 5-year backtest shows a typical error of ±10084.1%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1195% 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 →
±10084.1%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 New Hampshire is projected to stay roughly flat through 2028, near 0.00 (95% range 0.00–11). A 5-year backtest shows a typical error of ±10084.1%, with 100% of held-out values landing inside the 95% band.19662028
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 →
20240.000.0011
20250.000.0011
20260.000.0011
20270.000.0011
20280.000.0011

Herring Gull Survey Routes in New Hampshire

Routes recording Herring Gull in New Hampshire.
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 →
East Kingston520091999
Epsom419941967
Strafford420071967
Jefferson Hl319901967
Peterborough119971997
Brentwood119981966
Dover120231966
Concord119981978
Mt Chocorua119821982
Walpole119731973
Milan120071969
Clarksville120121990

Herring Gull Population Trend in Other States

alabamaalaskacaliforniacoloradoconnecticutdelawarefloridaidahoillinoisindianakansaslouisianamainemarylandmassachusettsmichiganminnesotamontananew-jerseynew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-carolinatexasvermontvirginiawashingtonwest-virginiawisconsin

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