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Species · California · BBS 2025 Release · 1966–2024

Lesser Scaup Population Trend in California

All statesWaterfowl

Lesser Scaup in California has edged up: up 24% on the route-weighted index since 1974.

+24%Since 1974TrendPercent 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 →
9Routes 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 →
48YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Lesser Scaup 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 →

No notable trend signals for Lesser Scaup in California. See the full index history below.

Lesser Scaup Population Forecast in California

If the recent trend holds, Lesser Scaup in California is projected to stay roughly flat through 2029, near 0.82 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±1861.9%, 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 →
0.82Projected 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 →
0.00–1.995% 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 →
±1861.9%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, Lesser Scaup in California is projected to stay roughly flat through 2029, near 0.82 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±1861.9%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20250.810.001.9
20260.810.001.9
20270.810.001.9
20280.820.001.9
20290.820.001.9

Lesser Scaup Survey Routes in California

Routes recording Lesser Scaup 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 →
Dorris1720191972
Crowder Flat820192019
Iron Gate220161988
Macdoel219981973
Ingalls219961996
Clear Lk Res220131984
Likely220242008
Big Bear119861986
Madeline120182016

Lesser Scaup Population Trend in Other States

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