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

House Sparrow Population Trend in Colorado

All statesGeneralists

House Sparrow in Colorado has collapsed: down 76% on the route-weighted index since 1970.

-76%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 →
109Routes 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 →
56YearsYears 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 collapsed in Colorado: down 76% 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 59% by 2029 — from 12 in 2024 to a central estimate of 4.9 (95% range 0.00–19). A 5-year backtest shows a typical error of ±51.7%, with 100% of held-out values landing inside the 95% band.

-59%Change by 2029TrendPercent 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 →
4.9Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1995% 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 →
±51.7%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, House Sparrow in Colorado is projected to fall about 59% by 2029 — from 12 in 2024 to a central estimate of 4.9 (95% range 0.00–19). A 5-year backtest shows a typical error of ±51.7%, with 100% of held-out values landing inside the 95% band.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 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 →
20256.90.0021
20266.40.0021
20275.90.0020
20285.40.0020
20294.90.0019

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 →
Hudson33420241988
Prospect Val16320001992
Pinneo11220191973
Nunn11220211995
Falfa8420241971
Adams Co.8120221989
Julesburg8120211998
Fruita7620071988
Fort Morgan6020241996
Mosca5120241992
Paonia4820241992
Pritchett4820241995
Yampa4620231970
Rush4320241983
Bennett4120181995
Flagler4120241997
Ellicott3820241994
Cortez 23820172009
Alamosa3620241988
Kiowa3420181968
Cortez3420081988
Last Chance 23220242017
Kirk3220231992
Sheridan Lak2920161995
Burlington2820242003

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 2026-05-22.