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Species · Colorado · BBS 2026 Release · 1966–2025

Western Bluebird Population Trend in Colorado

All statesForest birds

Western Bluebird in Colorado has risen sharply: up 71% on the route-weighted index since 1971.

+71%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 →
64Routes 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 →
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 Western Bluebird Trends in ColoradoNotable 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 →

Western Bluebird has risen sharply in Colorado: up 71% on the route-weighted index since 1971.

Western Bluebird Population Forecast in Colorado

If the recent trend holds, Western Bluebird in Colorado is projected to rise about 27% by 2030 — from 0.62 in 2025 to a central estimate of 0.79 (95% range 0.26–1.3). A 5-year backtest shows a typical error of ±90.7%, with 80% of held-out values landing inside the 95% band.

+27%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 →
0.79Projected 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 →
0.26–1.395% 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 →
±90.7%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 Colorado is projected to rise about 27% by 2030 — from 0.62 in 2025 to a central estimate of 0.79 (95% range 0.26–1.3). A 5-year backtest shows a typical error of ±90.7%, with 80% 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 →
20260.750.221.3
20270.760.231.3
20280.770.241.3
20290.780.251.3
20300.790.261.3

Western Bluebird Survey Routes in Colorado

Routes recording Western Bluebird in Colorado.
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 →
Elbert1320251998
Tarryall820251993
Kiowa 2820252019
Moffat719931978
Guffey720251990
Blackhead Pk720211991
Pleasant View620212021
Nucla620241999
Castleton519921991
Animas520031999
Kiowa420152005
Villegreen419981998
Maybell320062006
Harmony319901987
Mesaverde Np320251997
Cheesman Lk320251969
Colona320141972
Baxter Pass320242024
Groundhog Rs320122007
Pagosa Spgs219821969
Uncompahgre220251988
Steamboat L.220152003
Powderhorn220252014
Gribbles Prk220252000
Gold Hill 2220252022

Western Bluebird Population Trend in Other States

arizonacaliforniaidahomontananevadanew-mexicooregontexasutahwashingtonwyoming

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