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

Song Sparrow Population Trend in Colorado

All statesForest birds

Song Sparrow in Colorado has held roughly steady: down 7% on the route-weighted index since 1970.

-7%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 →
120Routes 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 Song 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 →

No notable trend signals for Song Sparrow in Colorado. See the full index history below.

Song Sparrow Population Forecast in Colorado

If the recent trend holds, Song Sparrow in Colorado is projected to fall about 27% by 2030 — from 4.0 in 2025 to a central estimate of 2.9 (95% range 0.86–4.9). A 5-year backtest shows a typical error of ±12.2%, with 100% of held-out values landing inside the 95% band.

-27%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 →
2.9Projected 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 →
0.86–4.995% 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 →
±12.2%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, Song Sparrow in Colorado is projected to fall about 27% by 2030 — from 4.0 in 2025 to a central estimate of 2.9 (95% range 0.86–4.9). A 5-year backtest shows a typical error of ±12.2%, 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 →
20262.90.885.0
20272.90.885.0
20282.90.875.0
20292.90.875.0
20302.90.864.9

Song Sparrow Survey Routes in Colorado

Routes recording Song 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 →
Yampa4320231969
Rifle Falls3420251998
Aspen2820251979
Ragged Mtn.2720251994
Stillwater Pass 22220252010
Castleton2020251988
Yellowjacket Pass1920251998
Buford1820251972
Heeney1820192017
Parlin1720251968
Moon Pass1720251998
Doyleville1220251988
Alamosa1220251988
Wilson Creek1120251990
Red Cliff1120251989
Lizard Head Pass1020252002
Heeney 21020252025
Blackhead Pk920251991
Rio Grnds Rs920241991
Deadman Rd.920251992
Stillwater Pass920091998
Wray Gulch820251988
Black Sulphur Cr820252015
Tarryall720251988
Dunckley Pas720251993

Song Sparrow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniaconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseeutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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