BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Purple Finch Population Trend in California

All statesForest birds

Purple Finch in California has edged down: down 17% on the route-weighted index since 1970.

-17%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 →
160Routes 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 Purple 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 →

No notable trend signals for Purple Finch in California. See the full index history below.

Purple Finch Population Forecast in California

If the recent trend holds, Purple Finch in California is projected to stay roughly flat through 2030, near 2.2 (95% range 1.3–3.1). A 5-year backtest shows a typical error of ±31.5%, with 80% of held-out values landing inside the 95% band.

-8%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 →
2.2Projected 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 →
1.3–3.195% 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 →
±31.5%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, Purple Finch in California is projected to stay roughly flat through 2030, near 2.2 (95% range 1.3–3.1). A 5-year backtest shows a typical error of ±31.5%, with 80% 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 →
20262.21.43.1
20272.21.33.1
20282.21.33.1
20292.21.33.1
20302.21.33.1

Purple Finch Survey Routes in California

Routes recording Purple 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 →
San Benito Mtn.2520092003
Point Reyes2120251970
Tuolumne Grove2120251972
Carmel Val1920251973
Crescent Cty1820251972
Greenhorn Mt1820081971
Tehama1820221973
Pescadero1820251992
Waterman Gap1520251975
Fallsvale1319811970
Sisquoc1320141970
Ora Loma1219721972
Honeydew1020171968
Riverton1020251973
Oneals1019731973
Santa Ynez920191969
Lumberyard920251976
Valyermo920191971
Crowley Lake919771975
Coulterville920191997
Lassen Park819811972
Cottage Spgs819701968
Crowder Flat820022002
Nubieber720071971
Colma719721968

Purple Finch Population Trend in Other States

alaskaconnecticutindianamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-dakotaohiooregonpennsylvaniarhode-islandvermontwashingtonwest-virginiawisconsin

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