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Species · California · BBS 2026 Release · 1966–2025

Cassin's Finch Population Trend in California

All statesForest birds

Cassin's Finch in California has fallen sharply: down 50% on the route-weighted index since 1970.

-50%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 →
86Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cassin's Finch 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 →

Cassin's Finch has fallen sharply in California: down 50% on the route-weighted index since 1970.

Cassin's Finch Population Forecast in California

If the recent trend holds, Cassin's Finch in California is projected to rise about 45% by 2030 — from 0.81 in 2025 to a central estimate of 1.2 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±139.1%, with 100% of held-out values landing inside the 95% band.

+45%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 →
1.2Projected 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 →
0.00–2.795% 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 →
±139.1%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, Cassin's Finch in California is projected to rise about 45% by 2030 — from 0.81 in 2025 to a central estimate of 1.2 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±139.1%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20261.20.002.7
20271.20.002.7
20281.20.002.7
20291.20.002.7
20301.20.002.7

Cassin's Finch Survey Routes in California

Routes recording Cassin's Finch 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 →
Lockwood Val2820061984
Crestview2320251997
Fallsvale1919751970
Macdoel1520191973
Crowder Flat1420192002
Eagle Lake1320251969
Valyermo1320191970
Green Valley1120191970
Cleveland Nf1120001996
Chilcoot1120241998
Fall River Mills1020072006
Goumaz1020111997
Last Chance1020191993
Big Bear919861969
Tahoe Nf919941993
Medicine Mtn.920212000
Mt Pinos 2820212005
Mt Shasta820191972
Dardanelle720191972
Lassen Park619891979
Mt Pinos620041969
Little Truckee620251997
Westville520251971
Woodfords520241974
Kings Canyon519721972

Cassin's Finch Population Trend in Other States

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