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

Sage Thrasher Population Trend in Colorado

All statesGeneralists

Sage Thrasher in Colorado has surged: up 798% on the route-weighted index since 1970.

+798%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 →
66Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Sage Thrasher 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 →

Sage Thrasher has surged in Colorado: up 798% on the route-weighted index since 1970.

Sage Thrasher Population Forecast in Colorado

If the recent trend holds, Sage Thrasher in Colorado is projected to fall about 13% by 2029 — from 4.5 in 2024 to a central estimate of 3.9 (95% range 0.94–6.9). A 5-year backtest shows a typical error of ±19.7%, with 100% of held-out values landing inside the 95% band.

-13%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 →
3.9Projected 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 →
0.94–6.995% 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 →
±19.7%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, Sage Thrasher in Colorado is projected to fall about 13% by 2029 — from 4.5 in 2024 to a central estimate of 3.9 (95% range 0.94–6.9). A 5-year backtest shows a typical error of ±19.7%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20253.90.936.9
20263.90.936.9
20273.90.936.9
20283.90.946.9
20293.90.946.9

Sage Thrasher Survey Routes in Colorado

Routes recording Sage Thrasher 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 →
Walden6220241990
Dinosaur4820241995
Browns Park4620241992
Maybell3720241972
Great Divide3720241974
Powderhorn3220231994
Antonito2820041995
Lay2620241996
Blanca2419871979
Basin2220241995
San Luis2020241991
Mesita1920242005
Mosca1920241992
Wilson Creek1820241990
Moffat1320241970
Doyleville1320241988
Cochetopa Pass1320241998
Yellowjacket Pass1120241999
Westcliffe1020151999
Yampa920231970
Alamosa920241988
Rosevale820242010
Paonia720241992
Lost Lake320231990
De Beque320242024

Sage Thrasher Population Trend in Other States

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