BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

Purple Finch In Sierra Nevada

All regionsSierra NevadaGeneralists

Purple Finch in Sierra Nevada has fallen sharply: down 70% on the route-weighted index since 1970.

-70%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 →
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 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 70% 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 71% by 2029 — from 2.8 in 2024 to a central estimate of 0.81 (95% range 0.00–4.5). A 5-year backtest shows a typical error of ±65%, with 100% of held-out values landing inside the 95% band.

-71%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 →
0.81Projected 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 →
0.00–4.595% 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 →
±65%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 71% by 2029 — from 2.8 in 2024 to a central estimate of 0.81 (95% range 0.00–4.5). A 5-year backtest shows a typical error of ±65%, with 100% 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 →
20251.30.005.0
20261.20.004.8
20271.00.004.7
20280.930.004.6
20290.810.004.5

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 →
Greenhorn MtCALIFORNIA182008
Tuolumne GroveCALIFORNIA162024
RivertonCALIFORNIA132023
CoultervilleCALIFORNIA92019
Lassen ParkCALIFORNIA81981
Cottage SpgsCALIFORNIA81970
PlacervilleCALIFORNIA62024
WestvilleCALIFORNIA52024
GeneseeCALIFORNIA52024
LakeshoreCALIFORNIA52024
WawonaCALIFORNIA52024
LumberyardCALIFORNIA42023
JohnsvilleCALIFORNIA32024
SattleyCALIFORNIA32008
WoodfordsCALIFORNIA22024
Silver CityCALIFORNIA22013
Kings CanyonCALIFORNIA22024
DownievilleCALIFORNIA22023
Meadow ValleyCALIFORNIA22024
Forest HillCALIFORNIA22022
StrawberryCALIFORNIA22019
Eagle LakeCALIFORNIA12023
DardanelleCALIFORNIA12019
Bass LakeCALIFORNIA12019
Butte MeadowCALIFORNIA12012

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