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

American Wigeon Population Trend in California

All statesWaterfowl

American Wigeon in California has fallen sharply: down 75% on the route-weighted index since 1973.

-75%Since 1973TrendPercent 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 →
19Routes 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 →
44YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable American Wigeon Trends in CaliforniaNotable 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 →

American Wigeon has fallen sharply in California: down 75% on the route-weighted index since 1973.

American Wigeon Population Forecast in California

If the recent trend holds, American Wigeon in California is projected to stay roughly flat through 2026, near 0.02 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±81.2%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2026TrendPercent 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 →
0.02Projected 2026 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 →
±81.2%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, American Wigeon in California is projected to stay roughly flat through 2026, near 0.02 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±81.2%, with 100% of held-out values landing inside the 95% band.19712026
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 →
20220.030.000.12
20230.030.000.11
20240.020.000.11
20250.020.000.11
20260.020.000.11

American Wigeon Survey Routes in California

Routes recording American Wigeon in California.
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 →
Clear Lk Res720011983
Iron Gate419941994
Madeline420112011
Riovista319761976
Crowder Flat320182016
Dorris320171975
Nubieber220032003
Hughson220101971
Likely220141976
Goumaz220112011
Macdoel219931993
Ingalls220011973
Crowley Lake120211980
Sattley119721972
Davis Creek119931993
Lockwood119961996
Cedarville119751975
Ravendale119831973
Benton120152015

American Wigeon Population Trend in Other States

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