BirdAnalyst
Species · Idaho · BBS 2025 Release · 1966–2024

California Gull Population Trend in Idaho

All statesWetland birds

California Gull in Idaho has collapsed: down 94% on the route-weighted index since 1971.

-94%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 →
26Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable California Gull Trends in IdahoNotable 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 →

California Gull has collapsed in Idaho: down 94% on the route-weighted index since 1971.

California Gull Population Forecast in Idaho

If the recent trend holds, California Gull in Idaho is projected to fall about 100% by 2029 — from 0.44 in 2024 to a central estimate of 0.00 (95% range 0.00–30). A 5-year backtest shows a typical error of ±3575.2%, with 100% of held-out values landing inside the 95% band.

-100%Change 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 →
0.00–3095% 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 →
±3575.2%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 Idaho is projected to fall about 100% by 2029 — from 0.44 in 2024 to a central estimate of 0.00 (95% range 0.00–30). A 5-year backtest shows a typical error of ±3575.2%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.000.0030
20260.000.0030
20270.000.0030
20280.000.0030
20290.000.0030

California Gull Survey Routes in Idaho

Routes recording California Gull in Idaho.
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 →
Henry12319831973
Cascade12019841983
Springfield6520181969
Pocatello3020191979
Blacks Creek2320151987
Mud Lake2220181988
Tractor Flat1120241986
Blackft Res820181984
Glenns Ferry819861986
Craters619961987
Circular Bu520032003
Dubois519901969
Alturas519691969
Acequia320121979
Preston320171988
Cape Horn219971997
Cedar Hill220211990
Kyle Canyon119861986
Leadore120122012
Ririe119961974
Crane Creek119911988
Iron Springs120112005
Featherville120031994
Picabo120141990
Cabarton120001987

California Gull Population Trend in Other States

alaskacaliforniacoloradominnesotamontananevadanew-mexiconorth-dakotaoregonsouth-dakotautahwashingtonwyoming

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