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

Swainson's Thrush Population Trend in Colorado

All statesForest birds

Swainson's Thrush in Colorado has surged: up 200% on the route-weighted index since 1974.

+200%Since 1974
49Routes In State
51Years

Notable Swainson's Thrush Trends in Colorado

long arc increasecomputed index

Swainson's Thrush has surged in Colorado: up 200% on the route-weighted index since 1974.

Swainson's Thrush Population Forecast in Colorado

If the recent trend holds, Swainson's Thrush in Colorado is projected to stay roughly flat through 2029, near 0.40 (95% range 0.07–0.73). A 5-year backtest shows a typical error of ±26.4%, with 100% of held-out values landing inside the 95% band.

+9%Change by 2029
0.40Projected 2029 index
0.07–0.7395% range
±26.4%Backtest error
19702029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.390.060.72
20260.400.070.73
20270.400.070.73
20280.400.070.73
20290.400.070.73

Swainson's Thrush Survey Routes in Colorado

Routes recording Swainson's Thrush in Colorado.
Aspen920241979
Yampa620231975
Parlin520221974
Stillwater Pass 2520242011
Dunckley Pas520241992
Rifle Falls520211998
Harmony419751975
Steamboat L.320242024
Comanche Pk320241996
Como320211994
Deadman Rd.320242013
Lost Lake220221990
Doyleville220211998
Buffalo Park220231992
Flattops220191992
Guanella Pas220241992
Pinon219951994
Nucla219991999
Lizard Head Pass220242001
Lake City 2220212018
Douglas Pass120162016
Buford120241987
Cheesman Lk120002000
Abarr119701970
Delta119741973

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniaconnecticutidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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