BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Mountain Bluebird Population Analysis

TurdidaeForest birdsSialia currucoides

Mountain Bluebird has surged: up 278% on the route-weighted index since 1969.

+278%Since 1969TrendPercent 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 →
773RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Mountain Bluebird

The Mountain Bluebird (Sialia currucoides) is a North American member of the Thrushes (Turdidae). In this analysis it is grouped with the forest birds.

Size
6–11 in long (15–28 cm) — a medium songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 773 Breeding Bird Survey routes across 15 states, most concentrated in the Southern Rockies / Colorado Plateau.
Family
Turdidae · Forest birds

Notable Mountain Bluebird TrendsNotable 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 increasecomputed 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 surged in surveyed states: up 278% on the route-weighted index since 1969.

Mountain Bluebird Population Forecast

If the recent trend holds, Mountain Bluebird is projected to rise about 25% by 2030 — from 0.72 in 2025 to a central estimate of 0.90 (95% range 0.60–1.2). A 5-year backtest shows a typical error of ±52.5%, with 20% of held-out values landing inside the 95% band.

+25%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 →
0.90Projected 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 →
0.60–1.295% 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 →
±52.5%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 is projected to rise about 25% by 2030 — from 0.72 in 2025 to a central estimate of 0.90 (95% range 0.60–1.2). A 5-year backtest shows a typical error of ±52.5%, with 20% of held-out values landing inside the 95% band.19672030
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 →
20260.860.561.2
20270.870.571.2
20280.880.581.2
20290.890.591.2
20300.900.601.2

Where the Mountain Bluebird Is Detected

BBS routes recording Mountain Bluebird, sized by most recent count.

Mountain Bluebird Population Trend by State

Mountain Bluebird population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alaskainsufficient datan/a3
Arizona-77%197027
California-5%197158
Colorado+166%1970114
Idaho-14%197149
Montana+43%197088
Nebraska-86%19824
Nevada-45%197024
New Mexico-43%197046
North Dakota+317%197411
Oregon-41%197080
South Dakota+149%196923
Utah+68%197095
Washington+340%197034
Wyoming+185%1970117

Mountain Bluebird Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Mountain Bluebird population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest-72%197017
Great Basin-16%1970148
Northern Rockies-8%1970208
Prairie Potholes-70%198710
Sierra Nevada-53%197123
Southern Rockies / Colorado Plateau+54%1970226
Badlands and Prairies+36%196990
Shortgrass Prairie-55%197022
Coastal California-86%19718
Sierra Madre Occidental-38%197012
Chihuahuan Desert-94%19745

Mountain Bluebird Conservation Status

Our route-weighted index shows it up about 278% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.