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

Western Bluebird In Sierra Nevada

All regionsSierra NevadaForest birds

Western Bluebird in Sierra Nevada has increased: up 40% on the route-weighted index since 1972.

+40%Since 1972TrendPercent 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 →
33Routes 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 →
54YearsYears 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 →

No notable trend signals for Western Bluebird in Sierra Nevada. See the full index history below.

Western Bluebird In Sierra Nevada Population Forecast

If the recent trend holds, Western Bluebird in Sierra Nevada is projected to fall about 35% by 2029 — from 1.7 in 2024 to a central estimate of 1.1 (95% range 0.00–2.3). A 5-year backtest shows a typical error of ±37.1%, with 100% of held-out values landing inside the 95% band.

-35%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 →
1.1Projected 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 →
0.00–2.395% 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 →
±37.1%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, Western Bluebird in Sierra Nevada is projected to fall about 35% by 2029 — from 1.7 in 2024 to a central estimate of 1.1 (95% range 0.00–2.3). A 5-year backtest shows a typical error of ±37.1%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20251.10.002.3
20261.10.002.3
20271.10.002.3
20281.10.002.3
20291.10.002.3

Routes In Sierra Nevada

Routes recording Western Bluebird 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 →
Hat CreekCALIFORNIA122018
Bass LakeCALIFORNIA82019
LakeshoreCALIFORNIA52024
Silver CityCALIFORNIA42013
Tuolumne GroveCALIFORNIA42024
SattleyCALIFORNIA42024
GeneseeCALIFORNIA42024
Pollock PinesCALIFORNIA42024
Pine MountainCALIFORNIA42017
WawonaCALIFORNIA32024
Eagle LakeCALIFORNIA22024
Greenhorn MtCALIFORNIA22008
Kings CanyonCALIFORNIA21990
Butte MeadowCALIFORNIA22013
DownievilleCALIFORNIA22013
RivertonCALIFORNIA22012
Forest HillCALIFORNIA22022
PlacervilleCALIFORNIA22024
CoultervilleCALIFORNIA22019
Lassen ParkCALIFORNIA11980
WestvilleCALIFORNIA12021
Cottage SpgsCALIFORNIA11969
JohnsvilleCALIFORNIA12023
WoodfordsCALIFORNIA12024
LumberyardCALIFORNIA12024

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