BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

Cassin's Sparrow Population Trend in Colorado

All statesGrassland birds

Cassin's Sparrow in Colorado has surged: up 263% on the route-weighted index since 1970.

+263%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 →
59Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cassin's Sparrow 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 →

Cassin's Sparrow has surged in Colorado: up 263% 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 stay roughly flat through 2030, near 6.1 (95% range 0.00–20). A 5-year backtest shows a typical error of ±40.7%, with 100% of held-out values landing inside the 95% band.

-10%Change by 2030TrendPercent 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 →
6.1Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–2095% 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 →
±40.7%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, Cassin's Sparrow in Colorado is projected to stay roughly flat through 2030, near 6.1 (95% range 0.00–20). A 5-year backtest shows a typical error of ±40.7%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20266.60.0021
20276.50.0021
20286.40.0021
20296.20.0021
20306.10.0020

Cassin's Sparrow Survey Routes in Colorado

Routes recording Cassin's Sparrow 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 →
Pritchett12220251995
Crowley11120241989
Campo9220251988
Boyero8720171979
Gilpin8420251970
Karval6220251995
Edison5820251988
Neegrande4920251992
Timpas4820251995
Pinneo4220251973
Edler4120251992
Villegreen3720241988
Ellicott3720251994
Rockport3420241996
Abarr2920241970
Haswell2920241992
Ninaview2920241994
Kirk2720231992
Rush2520251983
Lamar2020241973
Trinchera2020251990
Cone Mtn2020241988
Arsenal 21220252017
Two Buttes1020251973
Hudson920251988

Cassin's Sparrow Population Trend in Other States

arizonaarkansascaliforniakansasnebraskanew-mexicooklahomatexaswyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.