BirdAnalyst
Species · BCR 16 · BBS 2025 Release · 1966–2024

Ring-billed Gull In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauWetland birds

Ring-billed Gull in Southern Rockies / Colorado Plateau has fallen sharply: down 75% on the route-weighted index since 1991.

-75%Since 1991TrendPercent 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 →
26Routes 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 →
28YearsYears 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 →

Ring-billed Gull has fallen sharply in Southern Rockies / Colorado Plateau: down 75% on the route-weighted index since 1991.

Forecast

If the recent trend holds, Ring-billed Gull in Southern Rockies / Colorado Plateau is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.27). A 5-year backtest shows a typical error of ±210.5%, 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 →
0.00Projected 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 →
0.00–0.2795% 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 →
±210.5%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 Southern Rockies / Colorado Plateau is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.27). A 5-year backtest shows a typical error of ±210.5%, with 100% of held-out values landing inside the 95% band.19832029
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 →
20250.010.000.28
20260.010.000.28
20270.000.000.27
20280.000.000.27
20290.000.000.27

Routes In Southern Rockies / Colorado Plateau

Routes recording Ring-billed Gull in Southern Rockies / Colorado Plateau.
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 →
HarmonyCOLORADO142023
Stillwater PassCOLORADO122007
Cortez 2COLORADO122013
VernalUTAH82007
TarryallCOLORADO42019
TincupCOLORADO42019
Red Spur Mtn.UTAH42000
WaldenCOLORADO32024
Lost LakeCOLORADO32022
Steamboat L.COLORADO32008
Navajo LakeUTAH21997
BrookhurstWYOMING22015
Sybille CynWYOMING22024
FruitaCOLORADO12001
AlamosaCOLORADO12002
San LuisCOLORADO12022
Groundhog RsCOLORADO12004
Baxter PassCOLORADO12000
ComoCOLORADO12021
AntonitoCOLORADO12000
Piceance BasinCOLORADO12003
Rifle FallsCOLORADO11998
Cochetopa PassCOLORADO12013
Stillwater Pass 2COLORADO12010
KamasUTAH12015

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