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Species · Colorado · BBS 2025 Release · 1966–2024

Black-throated Gray Warbler Population Trend in Colorado

All statesForest birds

Black-throated Gray Warbler in Colorado has surged: up 215% on the route-weighted index since 1975.

+215%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 →
40Routes 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 →
48YearsYears 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-throated Gray Warbler 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-throated Gray Warbler has surged in Colorado: up 215% on the route-weighted index since 1975.

Black-throated Gray Warbler Population Forecast in Colorado

If the recent trend holds, Black-throated Gray Warbler in Colorado is projected to rise about 17% by 2029 — from 0.59 in 2024 to a central estimate of 0.69 (95% range 0.39–0.99). A 5-year backtest shows a typical error of ±33.8%, with 80% of held-out values landing inside the 95% band.

+17%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 →
0.69Projected 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 →
0.39–0.9995% 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 →
±33.8%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-throated Gray Warbler in Colorado is projected to rise about 17% by 2029 — from 0.59 in 2024 to a central estimate of 0.69 (95% range 0.39–0.99). A 5-year backtest shows a typical error of ±33.8%, with 80% of held-out values landing inside the 95% band.19732029
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 →
20250.650.350.95
20260.660.360.96
20270.670.370.97
20280.680.380.98
20290.690.390.99

Black-throated Gray Warbler Survey Routes in Colorado

Routes recording Black-throated Gray Warbler 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 →
Wray Gulch1820231988
Angora1520241998
Baxter Pass1220241994
Mesaverde Np920241996
Dinosaur520241995
Douglas Pass420241982
Blackhead Pk420192019
Wilson Creek320191996
Nucla320242000
Rosevale220242009
Uncompahgre220182017
Basin220191999
Browns Park220241995
Pinon220212013
Rifle Falls220181998
Cone Mtn220182018
Maybell120242004
Buford120241973
Aspen120141979
Delta120211973
Falfa120012001
Villegreen120002000
Gribbles Prk120212007
Animas119961996
South Fork120012001

Black-throated Gray Warbler Population Trend in Other States

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