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Species · Colorado · BBS 2026 Release · 1966–2025

Black-headed Grosbeak Population Trend in Colorado

All statesForest birds

Black-headed Grosbeak in Colorado has surged: up 263% on the route-weighted index since 1970.

+263%Since 1970TrendPercent 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 →
114Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-headed Grosbeak 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 →

Black-headed Grosbeak has surged in Colorado: up 263% on the route-weighted index since 1970.

Black-headed Grosbeak Population Forecast in Colorado

If the recent trend holds, Black-headed Grosbeak in Colorado is projected to fall about 16% by 2030 — from 3.4 in 2025 to a central estimate of 2.9 (95% range 1.9–3.8). A 5-year backtest shows a typical error of ±13%, with 100% of held-out values landing inside the 95% band.

-16%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 →
2.9Projected 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 →
1.9–3.895% 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 →
±13%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, Black-headed Grosbeak in Colorado is projected to fall about 16% by 2030 — from 3.4 in 2025 to a central estimate of 2.9 (95% range 1.9–3.8). A 5-year backtest shows a typical error of ±13%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20262.71.83.6
20272.71.83.7
20282.81.93.7
20292.81.93.7
20302.91.93.8

Black-headed Grosbeak Survey Routes in Colorado

Routes recording Black-headed Grosbeak 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 →
Walsenburg5920251994
Mesaverde Np4520251996
Cokedale2120251995
Animas2120041996
Mcphee Res.2020251996
Blackhead Pk1720251991
Douglas Pass1220241985
Wilson Creek1220251990
Baxter Pass1220241996
Trinchera1020251990
Wet Mtns.1020251993
Animas 2920252005
Paonia820251992
Rifle Falls820251998
Dunckley Pas720251992
Fox Creek720251993
Como720252018
Tarryall620252007
Cortez620081988
Gold Hill620121998
Ludlow620251998
Yampa520231987
Piedra520251992
Comanche Pk520241995
Owl Creek Pass520251998

Black-headed Grosbeak Population Trend in Other States

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