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Species · Colorado · BBS 2025 Release · 1966–2024

Western Bluebird Population Trend in Colorado

All statesForest birds

Western Bluebird in Colorado has risen sharply: up 52% on the route-weighted index since 1971.

+52%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 →
63Routes 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 →
53YearsYears 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 52% 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 60% by 2029 — from 0.49 in 2024 to a central estimate of 0.79 (95% range 0.25–1.3). A 5-year backtest shows a typical error of ±95.3%, with 80% of held-out values landing inside the 95% band.

+60%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 →
0.79Projected 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 →
0.25–1.395% 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 →
±95.3%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, Western Bluebird in Colorado is projected to rise about 60% by 2029 — from 0.49 in 2024 to a central estimate of 0.79 (95% range 0.25–1.3). A 5-year backtest shows a typical error of ±95.3%, with 80% 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 →
20250.760.221.3
20260.770.231.3
20270.770.231.3
20280.780.241.3
20290.790.251.3

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 →
Elbert1320241998
Moffat719931978
Uncompahgre720221988
Blackhead Pk720211991
Cheesman Lk620181969
Tarryall620211993
Pleasant View620212021
Nucla620241999
Castleton519921991
Animas520031999
Kiowa 2520242019
Ludlow520161998
Mesaverde Np420241997
Kiowa420152005
Villegreen419981998
Maybell320062006
Harmony319901987
Colona320141972
Guffey320241990
Baxter Pass320242024
Walsenburg320241995
Groundhog Rs320122007
Falfa220231972
Pagosa Spgs219821969
Steamboat L.220152003

Western Bluebird Population Trend in Other States

arizonacaliforniaidahomontananevadanew-mexicooregontexasutahwashingtonwyoming

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