BirdAnalyst
Species · BCR 15 · BBS 2026 Release · 1966–2025

Purple Finch In Sierra Nevada

All regionsSierra NevadaForest birds

Purple Finch in Sierra Nevada has fallen sharply: down 68% on the route-weighted index since 1970.

-68%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 →
36Routes In RegionSurvey 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 SignalsNotable 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 →

Purple Finch has fallen sharply in Sierra Nevada: down 68% on the route-weighted index since 1970.

Purple Finch In Sierra Nevada Population Forecast

If the recent trend holds, Purple Finch in Sierra Nevada is projected to fall about 78% by 2030 — from 4.4 in 2025 to a central estimate of 0.95 (95% range 0.00–4.7). A 5-year backtest shows a typical error of ±70.9%, with 80% of held-out values landing inside the 95% band.

-78%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 →
0.95Projected 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 →
0.00–4.795% 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 →
±70.9%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 Sierra Nevada is projected to fall about 78% by 2030 — from 4.4 in 2025 to a central estimate of 0.95 (95% range 0.00–4.7). A 5-year backtest shows a typical error of ±70.9%, 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 →
20261.40.005.1
20271.30.005.0
20281.20.004.9
20291.10.004.8
20300.950.004.7

Routes In Sierra Nevada

Routes recording Purple Finch in Sierra Nevada.
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 →
Tuolumne GroveCALIFORNIA212025
Greenhorn MtCALIFORNIA182008
RivertonCALIFORNIA102025
LumberyardCALIFORNIA92025
CoultervilleCALIFORNIA92019
Lassen ParkCALIFORNIA81981
Cottage SpgsCALIFORNIA81970
WawonaCALIFORNIA62025
GeneseeCALIFORNIA52024
LakeshoreCALIFORNIA52024
PaxtonCALIFORNIA52025
WestvilleCALIFORNIA42025
JohnsvilleCALIFORNIA42025
Forest HillCALIFORNIA42025
PlacervilleCALIFORNIA42025
SattleyCALIFORNIA32008
Meadow ValleyCALIFORNIA32025
Pollock PinesCALIFORNIA32025
Silver CityCALIFORNIA22013
Kings CanyonCALIFORNIA22024
DownievilleCALIFORNIA22025
Little TruckeeCALIFORNIA22025
StrawberryCALIFORNIA22019
Eagle LakeCALIFORNIA12023
DardanelleCALIFORNIA12019

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