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Species · California · BBS 2025 Release · 1966–2024

Clark's Nutcracker Population Trend in California

All statesGeneralists

Clark's Nutcracker in California has fallen sharply: down 64% on the route-weighted index since 1971.

-64%Since 1971TrendPercent 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 →
50Routes 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 Clark's Nutcracker 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 →

Clark's Nutcracker has fallen sharply in California: down 64% on the route-weighted index since 1971.

Clark's Nutcracker Population Forecast in California

If the recent trend holds, Clark's Nutcracker in California is projected to rise about 102% by 2029 — from 0.26 in 2024 to a central estimate of 0.52 (95% range 0.04–1.00). A 5-year backtest shows a typical error of ±69.2%, with 100% of held-out values landing inside the 95% band.

+102%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 →
0.52Projected 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 →
0.04–1.0095% 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 →
±69.2%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, Clark's Nutcracker in California is projected to rise about 102% by 2029 — from 0.26 in 2024 to a central estimate of 0.52 (95% range 0.04–1.00). A 5-year backtest shows a typical error of ±69.2%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.520.041.00
20260.520.041.00
20270.520.041.00
20280.520.041.00
20290.520.041.00

Clark's Nutcracker Survey Routes in California

Routes recording Clark's Nutcracker 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 →
Big Bear1919861969
Hat Creek1020061974
Lassen Park819891972
Hullville820061988
Last Chance820191993
Pine Mountain720171997
Crestview720241997
Fallsvale519721972
Fall River Mills420062006
Goumaz420111999
Little Truckee420231998
Mt Shasta420191972
Benton420241977
Mt Pinos 2320152006
Mt Pinos320041970
Bridgeport319771972
Medicine Mtn.320152000
Green Valley220161971
Eagle Lake220241971
White River219801980
Dardanelle220191972
Big Pine219991993
Crowley Lake220241976
Meadow Valley220082008
Tehama219741974

Clark's Nutcracker Population Trend in Other States

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