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

Bufflehead Population Trend in California

All statesWaterfowl

Bufflehead in California has surged: up 112% on the route-weighted index since 1988.

+112%Since 1988TrendPercent 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 →
13Routes 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 →
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 Bufflehead 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 Bufflehead in California. See the full index history below.

Bufflehead Population Forecast in California

If the recent trend holds, Bufflehead in California is projected to stay roughly flat through 2029, near 0.06 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±154.4%, with 80% 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 →
0.06Projected 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 →
0.00–0.1395% 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 →
±154.4%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, Bufflehead in California is projected to stay roughly flat through 2029, near 0.06 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±154.4%, with 80% of held-out values landing inside the 95% band.19812029
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 →
20250.060.000.13
20260.060.000.13
20270.060.000.13
20280.060.000.13
20290.060.000.13

Bufflehead Survey Routes in California

Routes recording Bufflehead 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 →
Dorris1420171981
Chilcoot519981998
Iron Gate220161996
Clear Lk Res220181984
Crowder Flat220132002
Madeline220242016
Sattley219991998
Meadow Valley120242016
Tehama119931993
Nubieber119951995
Davis Creek120122012
Whiskeytown120062006
Genesee120102010

Bufflehead Population Trend in Other States

alaskacoloradoidahominnesotamontananevadanorth-dakotaoregonsouth-dakotautahwashingtonwisconsinwyoming

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