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Species · California · BBS 2026 Release · 1966–2025

Rufous-crowned Sparrow Population Trend in California

All statesArid-land birds

Rufous-crowned Sparrow in California has surged: up 382% on the route-weighted index since 1972.

+382%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 →
74Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Rufous-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 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 →

Rufous-crowned Sparrow has surged in California: up 382% on the route-weighted index since 1972.

Rufous-crowned Sparrow Population Forecast in California

If the recent trend holds, Rufous-crowned Sparrow in California is projected to stay roughly flat through 2030, near 0.47 (95% range 0.21–0.72). A 5-year backtest shows a typical error of ±44.8%, with 20% of held-out values landing inside the 95% band.

+4%Change by 2030TrendPercent 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 →
0.47Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.21–0.7295% 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 →
±44.8%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, Rufous-crowned Sparrow in California is projected to stay roughly flat through 2030, near 0.47 (95% range 0.21–0.72). A 5-year backtest shows a typical error of ±44.8%, with 20% of held-out values landing inside the 95% band.19702030
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 →
20260.440.190.70
20270.450.200.70
20280.460.200.71
20290.460.210.71
20300.470.210.72

Rufous-crowned Sparrow Survey Routes in California

Routes recording Rufous-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 →
Elsinore Mtn1920251970
Santa Cruz I1819881988
Angelus Oaks920051993
Greenfield720251974
Silver City620132003
Red Bluff519951995
Lake Success519721972
Poway519801978
Hough Springs420072000
Sanger420232011
Lake Cachuma320161991
Forest Hill320251998
Orange Cove320121978
Lake Hemet 2320141993
Jofegan320232008
Joshua Tree219971991
White River219921973
Rumsey220081981
Tres Pinos220021985
Longvale220171980
Kernville220082008
Moraga219861986
Moreno220252012
Oneals220191981
Cal Hot Spgs220161993

Rufous-crowned Sparrow Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.