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

House Sparrow Population Trend in Colorado

All statesGeneralists

House Sparrow in Colorado has fallen sharply: down 75% on the route-weighted index since 1970.

-75%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 →
110Routes 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 House 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 declinecomputed 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 →

House Sparrow has fallen sharply in Colorado: down 75% on the route-weighted index since 1970.

House Sparrow Population Forecast in Colorado

If the recent trend holds, House Sparrow in Colorado is projected to fall about 68% by 2030 — from 16 in 2025 to a central estimate of 5.1 (95% range 0.00–20). A 5-year backtest shows a typical error of ±54.8%, with 100% of held-out values landing inside the 95% band.

-68%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 →
5.1Projected 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 →
±54.8%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, House Sparrow in Colorado is projected to fall about 68% by 2030 — from 16 in 2025 to a central estimate of 5.1 (95% range 0.00–20). A 5-year backtest shows a typical error of ±54.8%, 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 →
20267.10.0022
20276.60.0021
20286.10.0021
20295.60.0020
20305.10.0020

House Sparrow Survey Routes in Colorado

Routes recording House 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 →
Hudson31920251988
Two Buttes19920251973
Prospect Val16320001992
Nunn13120251995
Alamosa8620251988
Adams Co.8120221989
Julesburg8120211998
Bennett8120251995
Fruita7620071988
Falfa7120251971
Flagler6820251997
Ellicott6820251994
Mosca6520251992
Rush5620251983
Fort Morgan5220251996
Pritchett5120251995
Yampa4620231970
Moffat4320251973
Paonia4120251992
Cortez 23820172009
Fleming3720251968
Kiowa3420181968
Cortez3420081988
Kirk3220231992
Sheridan Lak2920161995

House Sparrow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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