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Species · Maryland · BBS 2025 Release · 1966–2024

Great Black-backed Gull Population Trend in Maryland

All statesWetland birds

Great Black-backed Gull in Maryland has held roughly steady: up 6% on the route-weighted index since 1975.

+6%Since 1975TrendPercent 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 →
11Routes 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 →
26YearsYears 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 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 Great Black-backed Gull in Maryland. See the full index history below.

Great Black-backed Gull Population Forecast in Maryland

If the recent trend holds, Great Black-backed Gull in Maryland is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±186.1%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.03Projected 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 →
0.00–0.1695% 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 →
±186.1%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, Great Black-backed Gull in Maryland is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±186.1%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.040.000.16
20260.040.000.16
20270.040.000.16
20280.040.000.16
20290.030.000.16

Great Black-backed Gull Survey Routes in Maryland

Routes recording Great Black-backed 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 →
Berlin420052005
Melitota320041975
Theodore219961973
Matthews220012001
Newark220241993
Sinepuxent219741974
Elkton120062006
Honga119981998
Madison119951995
Indiantown119971987
St. George'S Island120152015

Great Black-backed Gull Population Trend in Other States

connecticutdelawaremainemassachusettsnew-hampshirenew-jerseynew-yorknorth-carolinaohiorhode-islandvermontvirginia

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