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

Vesper Sparrow Population Trend in Colorado

All statesGrassland birds

Vesper Sparrow in Colorado has surged: up 17× on the route-weighted index since 1970.

17×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 →
125Routes 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 Vesper 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 →

Vesper Sparrow has surged in Colorado: up 17× on the route-weighted index since 1970.

Vesper Sparrow Population Forecast in Colorado

If the recent trend holds, Vesper Sparrow in Colorado is projected to rise about 24% by 2030 — from 7.8 in 2025 to a central estimate of 9.7 (95% range 5.3–14). A 5-year backtest shows a typical error of ±13.5%, with 100% of held-out values landing inside the 95% band.

+24%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 →
9.7Projected 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 →
5.3–1495% 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 →
±13.5%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, Vesper Sparrow in Colorado is projected to rise about 24% by 2030 — from 7.8 in 2025 to a central estimate of 9.7 (95% range 5.3–14). A 5-year backtest shows a typical error of ±13.5%, 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 →
20269.34.914
20279.45.014
20289.55.114
20299.65.214
20309.75.314

Vesper Sparrow Survey Routes in Colorado

Routes recording Vesper 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 →
Great Divide6920251974
Gribbles Prk4720251995
Mcphee Res.4320251996
Lay4220251996
Walden4120251990
Maybell4020251971
Dinosaur3720251995
Yellowjacket Pass3720251998
Browns Park3020251992
Wilson Creek2920251990
Gardner2820251998
Doyleville2620251988
Yampa2320231969
Blanca2319871980
Uncompahgre2220251988
Antonito2220041995
Moffat2120251970
San Luis2020251991
Paonia2020251992
Powderhorn1820251995
Lost Lake1720251993
Elbert1720251998
Wet Mtns.1620251993
Guffey1220251991
Colona 21220252015

Vesper Sparrow Population Trend in Other States

arizonacaliforniaconnecticutdelawareidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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