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

Purple Finch Population Trend in California

All statesGeneralists

Purple Finch in California has edged down: down 23% on the route-weighted index since 1970.

-23%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 →
159Routes 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 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 rise about 16% by 2029 — from 1.9 in 2024 to a central estimate of 2.2 (95% range 1.3–3.1). A 5-year backtest shows a typical error of ±38.8%, with 80% of held-out values landing inside the 95% band.

+16%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 →
2.2Projected 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 →
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 →
±38.8%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, Purple Finch in California is projected to rise about 16% by 2029 — from 1.9 in 2024 to a central estimate of 2.2 (95% range 1.3–3.1). A 5-year backtest shows a typical error of ±38.8%, with 80% 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 →
20252.21.33.1
20262.21.33.1
20272.21.33.1
20282.21.33.1
20292.21.33.1

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
Carmel Val2320241973
Pescadero2220241992
Greenhorn Mt1820081971
Tehama1820221973
Point Reyes1720231970
Tuolumne Grove1620241972
Waterman Gap1520241975
Fallsvale1319811970
Sisquoc1320141970
Riverton1320231973
Crescent Cty1220241972
Ora Loma1219721972
Honeydew1020171968
Oneals1019731973
Friday Ridge1020241995
Santa Ynez920191969
Valyermo920191971
Crowley Lake919771975
Coulterville920191997
Lassen Park819811972
Cottage Spgs819701968
Crowder Flat820022002
Nubieber720071971
Holmes720241968

Purple Finch Population Trend in Other States

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

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