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Species · BCR 14 · BBS 2025 Release · 1966–2024

Great Black-backed Gull In Atlantic Northern Forest

All regionsAtlantic Northern ForestWetland birds

Great Black-backed Gull in Atlantic Northern Forest has fallen sharply: down 59% on the route-weighted index since 1971.

-59%Since 1971TrendPercent 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 →
16Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
35YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

Great Black-backed Gull has fallen sharply in Atlantic Northern Forest: down 59% on the route-weighted index since 1971.

Great Black-backed Gull In Atlantic Northern Forest Population Forecast

If the recent trend holds, Great Black-backed Gull in Atlantic Northern Forest is projected to fall about 100% by 2012 — from 0.06 in 2007 to a central estimate of 0.00 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±78.6%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2012TrendPercent 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 2012 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1195% 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 →
±78.6%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, Great Black-backed Gull in Atlantic Northern Forest is projected to fall about 100% by 2012 — from 0.06 in 2007 to a central estimate of 0.00 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±78.6%, with 100% of held-out values landing inside the 95% band.19692012
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 →
20080.010.000.11
20090.000.000.11
20100.000.000.11
20110.000.000.11
20120.000.000.11

Routes In Atlantic Northern Forest

Routes recording Great Black-backed Gull in Atlantic Northern Forest.
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 →
HartfordMAINE71988
NewcastleMAINE42007
MedwayMAINE31979
BiddefordMAINE21975
DebloisMAINE21998
WestbrookMAINE11988
TurnerMAINE11996
WarrenMAINE11985
BrooksMAINE11993
HancockMAINE11987
CastineMAINE12000
CooperMAINE12007
Moose RiverMAINE11987
St DavidMAINE12005
JeffersonMAINE11996
Jefferson HlNEW-HAMPSHIRE11993

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