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Species · Maryland · BBS 2026 Release · 1966–2025

Herring Gull Population Trend in Maryland

All statesWetland birds

Herring Gull in Maryland has surged: up 391% on the route-weighted index since 1968.

+391%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 →
21Routes 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 →
53YearsYears 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 MarylandNotable 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 Herring Gull in Maryland. See the full index history below.

Herring Gull Population Forecast in Maryland

If the recent trend holds, Herring Gull in Maryland is projected to rise about 189% by 2030 — from 0.40 in 2025 to a central estimate of 1.1 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±1888.8%, with 100% of held-out values landing inside the 95% band.

+189%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 →
1.1Projected 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 →
0.00–3.495% 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 →
±1888.8%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, Herring Gull in Maryland is projected to rise about 189% by 2030 — from 0.40 in 2025 to a central estimate of 1.1 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±1888.8%, with 100% 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 →
20261.10.003.4
20271.10.003.4
20281.10.003.4
20291.10.003.4
20301.10.003.4

Herring Gull Survey Routes in Maryland

Routes recording Herring Gull in Maryland.
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 →
Indiantown8120141989
St. George'S Island1320172015
Newark1120251967
Mardela620002000
Sinepuxent519751970
Elkton419971969
Golden Hill420211971
Walnut220162004
Melitota219831966
Honga220251968
Madison220251972
Davidsnville220172017
Pleasant Val119871987
Jones119711970
Berlin120181987
Broomes Isl119711971
Piney Neck119671967
Fruitland119941994
Cokesbury120191996
Snow Hill119741974
Severna Park119981998

Herring Gull Population Trend in Other States

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

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