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

White-crowned Sparrow Population Trend in California

All statesGeneralists

White-crowned Sparrow in California has fallen sharply: down 62% on the route-weighted index since 1970.

-62%Since 1970TrendPercent 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 →
62Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable White-crowned Sparrow 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 →

White-crowned Sparrow has fallen sharply in California: down 62% on the route-weighted index since 1970.

White-crowned Sparrow Population Forecast in California

If the recent trend holds, White-crowned Sparrow in California is projected to fall about 24% by 2029 — from 0.65 in 2024 to a central estimate of 0.49 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±19.3%, with 100% of held-out values landing inside the 95% band.

-24%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 →
0.49Projected 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 →
0.00–1.295% 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 →
±19.3%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, White-crowned Sparrow in California is projected to fall about 24% by 2029 — from 0.65 in 2024 to a central estimate of 0.49 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±19.3%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20250.600.001.4
20260.570.001.3
20270.540.001.3
20280.520.001.3
20290.490.001.2

White-crowned Sparrow Survey Routes in California

Routes recording White-crowned Sparrow 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 →
Crescent Cty5420241972
Colma3019721968
Rio Dell2720121972
Navarro1620111973
Redwood N.P.1520101995
Bodega Bay1520211972
Tipton1319721972
Honeydew1220171968
Morro Bay1120191973
Martins Fy1120091976
Redwood N.P. 2720132012
Yokohl Val719731973
Fish Rock620141968
Last Chance620191998
Cp. Pendleton519911991
Dardanelle420191972
Bridgeport419731972
Deep Springs420191972
Waterman Gap419721972
Korbel420241972
Cottage Spgs319681968
Oak Grove319821982
Johnsville320192018
Fairfax320151972
Gazelle220102010

White-crowned Sparrow Population Trend in Other States

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