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

Cassin's Sparrow Population Trend in Colorado

All statesGrassland birds

Cassin's Sparrow in Colorado has surged: up 215% on the route-weighted index since 1970.

+215%Since 1970
59Routes In State
56Years

Notable Cassin's Sparrow Trends in Colorado

long arc increasecomputed index

Cassin's Sparrow has surged in Colorado: up 215% on the route-weighted index since 1970.

Cassin's Sparrow Population Forecast in Colorado

If the recent trend holds, Cassin's Sparrow in Colorado is projected to fall about 24% by 2029 — from 8.2 in 2024 to a central estimate of 6.2 (95% range 0.00–21). A 5-year backtest shows a typical error of ±44.1%, with 100% of held-out values landing inside the 95% band.

-24%Change by 2029
6.2Projected 2029 index
0.00–2195% range
±44.1%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
20256.80.0021
20266.60.0021
20276.50.0021
20286.40.0021
20296.20.0021

Cassin's Sparrow Survey Routes in Colorado

Routes recording Cassin's Sparrow in Colorado.
Crowley11120241989
Pritchett10220241995
Boyero8720171979
Campo8320191988
Timpas7420191995
Gilpin7020241970
Edison6520241988
Ellicott5720241994
Neegrande4620241992
Rush4420241983
Villegreen3720241988
Rockport3420241996
Abarr2920241970
Haswell2920241992
Ninaview2920241994
Kirk2720231992
Trinchera2420221990
Pinneo2320191973
Lamar2020241973
Edler2020241992
Cone Mtn2020241988
Cheyenne1920241990
Karval1820191995
Arsenal 21720242017
Two Buttes1720151973

Cassin's Sparrow Population Trend in Other States

arizonaarkansascaliforniakansasnebraskanew-mexicooklahomatexaswyoming

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