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

Brown Thrasher Population Trend in Colorado

All statesGeneralists

Brown Thrasher in Colorado has collapsed: down 81% on the route-weighted index since 1970.

-81%Since 1970
41Routes In State
53Years

Notable Brown Thrasher Trends in Colorado

long arc declinecomputed index

Brown Thrasher has collapsed in Colorado: down 81% on the route-weighted index since 1970.

Brown Thrasher Population Forecast in Colorado

If the recent trend holds, Brown Thrasher in Colorado is projected to rise about 19% by 2029 — from 0.11 in 2024 to a central estimate of 0.14 (95% range 0.00–0.43). A 5-year backtest shows a typical error of ±22.6%, with 100% of held-out values landing inside the 95% band.

+19%Change by 2029
0.14Projected 2029 index
0.00–0.4395% range
±22.6%Backtest error
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 index95% low95% high
20250.140.000.44
20260.140.000.44
20270.140.000.44
20280.140.000.44
20290.140.000.43

Brown Thrasher Survey Routes in Colorado

Routes recording Brown Thrasher in Colorado.
Julesburg520212002
Timpas520102000
Two Buttes419971984
Fort Morgan420231996
Kirk420232005
Last Chance319991968
Boyero320161995
Wildhorse L320141990
Burlington320242003
Prospect Val320001995
Rockport220242013
Sheridan Lak220161995
Grover220241995
Doyle Bridge219951992
Neegrande220241993
Maybell119711970
Harmony120121986
Briggsdale120222003
Pinneo120091973
Fleming120231968
Kiowa120151968
Abarr120231970
Parlin120162007
Lamar120111977
Prospect Valley 2120232003

Brown Thrasher Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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