BirdAnalyst
Species · BCR 11 · BBS 2026 Release · 1966–2025

California Gull In Prairie Potholes

All regionsPrairie PotholesWetland birds

California Gull in Prairie Potholes has surged: up 335% on the route-weighted index since 1971.

+335%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 →
39Routes 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 →
56YearsYears 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 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 →

California Gull has surged in Prairie Potholes: up 335% on the route-weighted index since 1971.

California Gull In Prairie Potholes Population Forecast

If the recent trend holds, California Gull in Prairie Potholes is projected to fall about 21% by 2030 — from 1.3 in 2025 to a central estimate of 1.0 (95% range 0.10–2.0). A 5-year backtest shows a typical error of ±99%, with 80% of held-out values landing inside the 95% band.

-21%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 →
1.0Projected 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 →
0.10–2.095% 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 →
±99%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, California Gull in Prairie Potholes is projected to fall about 21% by 2030 — from 1.3 in 2025 to a central estimate of 1.0 (95% range 0.10–2.0). A 5-year backtest shows a typical error of ±99%, with 80% of held-out values landing inside the 95% band.19682030
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 →
20260.990.051.9
20271.00.062.0
20281.00.082.0
20291.00.092.0
20301.00.102.0

Routes In Prairie Potholes

Routes recording California Gull in Prairie Potholes.
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 →
Douglas CrkNORTH-DAKOTA832025
Great FallsMONTANA92025
BuchananNORTH-DAKOTA82018
Ester LakeMONTANA62024
SacoMONTANA62023
DanzigNORTH-DAKOTA62008
Long LakeSOUTH-DAKOTA42004
GlasgowMONTANA32025
ReganNORTH-DAKOTA32006
Powers LakeNORTH-DAKOTA32022
BraddockNORTH-DAKOTA32023
Big StoneMINNESOTA22005
OswegoMONTANA22021
WhitlashMONTANA22016
Horsehead LkNORTH-DAKOTA22025
Lakota 2NORTH-DAKOTA22010
TurtonSOUTH-DAKOTA22009
Hay LakeMONTANA12021
SunburstMONTANA11998
VirgelleMONTANA12001
ClevelandMONTANA12015
HarlemMONTANA12021
MaltaMONTANA12021
RedstoneMONTANA12023
ShelbyMONTANA12019

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