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

Dusky Grouse Population Trend in Colorado

All statesGeneralists

Dusky Grouse in Colorado has collapsed: down 78% on the route-weighted index since 1975.

-78%Since 1975TrendPercent 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 →
42Routes 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 →
38YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Dusky Grouse 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 declinecomputed 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 →

Dusky Grouse has collapsed in Colorado: down 78% on the route-weighted index since 1975.

Dusky Grouse Population Forecast in Colorado

If the recent trend holds, Dusky Grouse in Colorado is projected to fall about 77% by 2029 — from 0.06 in 2024 to a central estimate of 0.01 (95% range 0.00–0.09). A 5-year backtest shows a typical error of ±58.4%, with 100% of held-out values landing inside the 95% band.

-77%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 →
0.01Projected 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 →
0.00–0.0995% 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 →
±58.4%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, Dusky Grouse in Colorado is projected to fall about 77% by 2029 — from 0.06 in 2024 to a central estimate of 0.01 (95% range 0.00–0.09). A 5-year backtest shows a typical error of ±58.4%, with 100% 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 →
20250.020.000.10
20260.020.000.10
20270.020.000.10
20280.010.000.10
20290.010.000.09

Dusky Grouse Survey Routes in Colorado

Routes recording Dusky Grouse 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 →
Pagosa Spgs519751975
Radium419981998
Dunckley Pas220241999
Yellowjacket Pass220182017
Colona 2220212015
Blackhead Pk220211991
Yampa120072007
Mount Evans120012001
Mesaverde Np120102001
Douglas Pass120242024
Aspen119981998
Cheesman Lk120151969
Delta119761976
Colona120071994
Summitville120242009
Walden120082006
Lost Lake120152015
Willow Peak120161992
Uncompahgre120231990
Castleton120131996
Steamboat L.120111998
Guffey120062006
Dolores Riv120152003
Ragged Mtn.120132006
Como120182017

Dusky Grouse Population Trend in Other States

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