BirdAnalyst
Species · Pennsylvania · BBS 2026 Release · 1966–2025

Ring-billed Gull Population Trend in Pennsylvania

All statesWetland birds

Ring-billed Gull in Pennsylvania has risen sharply: up 65% on the route-weighted index since 1979.

+65%Since 1979TrendPercent 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 →
22Routes 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 →
31YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Ring-billed Gull Trends in PennsylvaniaNotable 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 increasecomputed 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 →

Ring-billed Gull has risen sharply in Pennsylvania: up 65% on the route-weighted index since 1979.

Ring-billed Gull Population Forecast in Pennsylvania

If the recent trend holds, Ring-billed Gull in Pennsylvania is projected to fall about 32% by 2030 — from 0.22 in 2025 to a central estimate of 0.15 (95% range 0.00–0.87). A 5-year backtest shows a typical error of ±706.4%, with 100% of held-out values landing inside the 95% band.

-32%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 →
0.15Projected 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 →
0.00–0.8795% 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 →
±706.4%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, Ring-billed Gull in Pennsylvania is projected to fall about 32% by 2030 — from 0.22 in 2025 to a central estimate of 0.15 (95% range 0.00–0.87). A 5-year backtest shows a typical error of ±706.4%, 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 →
20260.160.000.88
20270.160.000.88
20280.150.000.88
20290.150.000.88
20300.150.000.87

Ring-billed Gull Survey Routes in Pennsylvania

Routes recording Ring-billed Gull in Pennsylvania.
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 →
Rosecrans3520022002
New Ringgold3120021970
Mount Joy2319961989
Sugar Grove1920252015
Espyville1620241993
Teepleville420012001
Wakena419901990
Wild Creek319961996
Kittanning319971997
Ferris Crnrs220241996
Austinville220072007
Harmonsburg119661966
N Washington120052004
Mawr Glen119951995
Millville119811981
Honesdale119921992
Greentown120191979
Beaver120112011
Parkwood120072007
Bald Eagle119901990
Middletown119941994
Drehersville119861986

Ring-billed Gull Population Trend in Other States

alabamaarizonacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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