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Species · Connecticut · BBS 2025 Release · 1966–2024

Great Black-backed Gull Population Trend in Connecticut

All statesWetland birds

Great Black-backed Gull in Connecticut has held roughly steady: up 7% on the route-weighted index since 1976.

+7%Since 1976TrendPercent 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 →
3Routes 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 →
25YearsYears 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 ConnecticutNotable 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 Connecticut. See the full index history below.

Great Black-backed Gull Population Forecast in Connecticut

If the recent trend holds, Great Black-backed Gull in Connecticut is projected to rise about 20% by 2028 — from 0.18 in 2023 to a central estimate of 0.22 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±237%, with 80% of held-out values landing inside the 95% band.

+20%Change 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 →
0.22Projected 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 →
0.00–0.4995% 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 →
±237%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 Connecticut is projected to rise about 20% by 2028 — from 0.18 in 2023 to a central estimate of 0.22 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±237%, with 80% of held-out values landing inside the 95% band.19732028
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 →
20240.210.000.49
20250.210.000.49
20260.220.000.49
20270.220.000.49
20280.220.000.49

Great Black-backed Gull Survey Routes in Connecticut

Routes recording Great Black-backed Gull in Connecticut.
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 →
Mystic220231973
Westbrook119941986
Mid Haddam120052005

Great Black-backed Gull Population Trend in Other States

delawaremainemarylandmassachusettsnew-hampshirenew-jerseynew-yorknorth-carolinaohiorhode-islandvermontvirginia

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