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

Redhead Population Trend in California

All statesWaterfowl

Redhead in California has surged: up 122% on the route-weighted index since 1972.

+122%Since 1972TrendPercent 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 →
22Routes 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 →
50YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Redhead 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 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 →

Redhead has surged in California: up 122% on the route-weighted index since 1972.

Redhead Population Forecast in California

If the recent trend holds, Redhead in California is projected to rise about 13× by 2029 — from 0.05 in 2024 to a central estimate of 0.70 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±413.5%, with 100% of held-out values landing inside the 95% band.

13×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 →
0.70Projected 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 →
0.00–1.795% 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 →
±413.5%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, Redhead in California is projected to rise about 13× by 2029 — from 0.05 in 2024 to a central estimate of 0.70 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±413.5%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20250.690.001.7
20260.700.001.7
20270.700.001.7
20280.700.001.7
20290.700.001.7

Redhead Survey Routes in California

Routes recording Redhead 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 →
Dorris5620191972
Niland3020101992
Big Bear2019811971
Glenn1020002000
Madeline1020182018
Crowder Flat820022002
Macdoel419981987
Tranquillity319971973
Hughson220172010
Likely220241990
Sattley219741974
Honey Lake220171994
Clear Lk Res220011972
Cedarville220191994
Yreka219931984
Benton220241979
Buena Vista219961996
Nubieber120181970
Gold Hill120072007
Davis Creek120102010
Ora Loma120242024
Ingalls119971984

Redhead Population Trend in Other States

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