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

Mountain Bluebird In Sierra Nevada

All regionsSierra NevadaForest birds

Mountain Bluebird in Sierra Nevada has fallen sharply: down 53% on the route-weighted index since 1971.

-53%Since 1971TrendPercent 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 →
23Routes 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 →

Mountain Bluebird has fallen sharply in Sierra Nevada: down 53% on the route-weighted index since 1971.

Mountain Bluebird In Sierra Nevada Population Forecast

If the recent trend holds, Mountain Bluebird in Sierra Nevada is projected to fall about 55% by 2030 — from 1.6 in 2025 to a central estimate of 0.73 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±42.9%, with 100% of held-out values landing inside the 95% band.

-55%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 →
0.73Projected 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 →
0.00–2.195% 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 →
±42.9%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, Mountain Bluebird in Sierra Nevada is projected to fall about 55% by 2030 — from 1.6 in 2025 to a central estimate of 0.73 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±42.9%, with 100% of held-out values landing inside the 95% band.19692030
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 →
20260.740.002.1
20270.730.002.1
20280.730.002.1
20290.730.002.1
20300.730.002.1

Routes In Sierra Nevada

Routes recording Mountain 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 →
GoumazCALIFORNIA142011
Eagle LakeCALIFORNIA122025
ChilcootCALIFORNIA112024
SattleyCALIFORNIA52025
Little TruckeeCALIFORNIA52025
Pine MountainCALIFORNIA42017
CrestviewCALIFORNIA42025
JohnsvilleCALIFORNIA32014
Tuolumne GroveCALIFORNIA32016
GeneseeCALIFORNIA22023
RivertonCALIFORNIA22004
Hat CreekCALIFORNIA22017
Pollock PinesCALIFORNIA22025
Last ChanceCALIFORNIA22019
Lassen ParkCALIFORNIA11988
WestvilleCALIFORNIA12023
DardanelleCALIFORNIA12019
WoodfordsCALIFORNIA12001
LumberyardCALIFORNIA12025
Greenhorn MtCALIFORNIA11984
LakeshoreCALIFORNIA12001
PaxtonCALIFORNIA12000
Meadow ValleyCALIFORNIA11999

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