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

Mountain Bluebird Population Trend in California

All statesForest birds

Mountain Bluebird in California has declined: down 31% on the route-weighted index since 1971.

-31%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 →
57Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Mountain Bluebird 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 Mountain Bluebird in California. See the full index history below.

Mountain Bluebird Population Forecast in California

If the recent trend holds, Mountain Bluebird in California is projected to rise about 134% by 2029 — from 0.23 in 2024 to a central estimate of 0.53 (95% range 0.14–0.92). A 5-year backtest shows a typical error of ±181.3%, with 40% of held-out values landing inside the 95% band.

+134%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 →
0.53Projected 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 →
0.14–0.9295% 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 →
±181.3%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 California is projected to rise about 134% by 2029 — from 0.23 in 2024 to a central estimate of 0.53 (95% range 0.14–0.92). A 5-year backtest shows a typical error of ±181.3%, with 40% 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 →
20250.520.130.91
20260.520.130.91
20270.520.130.91
20280.530.140.91
20290.530.140.92

Mountain Bluebird Survey Routes in California

Routes recording Mountain Bluebird 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 →
Ingalls2320011973
Bridgeport2119731972
Macdoel2020191973
Crowder Flat1620192002
Hackamore1420102000
Goumaz1420111997
Mt Shasta1220191975
Chilcoot1120241998
Sattley820151972
Tionesta620211997
Deep Springs620221972
Eagle Lake420241969
Fall River Mills420072000
Pine Mountain420171997
Bartle420151972
Tuolumne Grove320161975
Clear Lk Res320171972
Johnsville320141982
Nubieber220131972
Madeline220241998
Little Truckee220232004
Pollock Pines220242024
Alamar219971997
Last Chance220191993
Genesee220231972

Mountain Bluebird Population Trend in Other States

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