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

Vesper Sparrow Population Trend in Colorado

All statesGrassland birds

Vesper Sparrow in Colorado has surged: up 19× on the route-weighted index since 1970.

19×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 →
124Routes 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 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 19× 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 13% by 2029 — from 8.6 in 2024 to a central estimate of 9.7 (95% range 5.3–14). A 5-year backtest shows a typical error of ±17.9%, with 100% of held-out values landing inside the 95% band.

+13%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 →
9.7Projected 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 →
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 →
±17.9%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 13% by 2029 — from 8.6 in 2024 to a central estimate of 9.7 (95% range 5.3–14). A 5-year backtest shows a typical error of ±17.9%, 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 →
20259.44.914
20269.55.014
20279.55.114
20289.65.214
20299.75.314

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 →
Walden7320241990
Great Divide6220241974
Gribbles Prk5720241995
Dinosaur4720241995
Maybell3920241971
Yellowjacket Pass3720241998
San Luis3420241991
Uncompahgre2820241988
Mcphee Res.2820241996
Lay2720241996
Doyleville2620241988
Angora2420241998
Mesita2420242005
Yampa2320231969
Blanca2319871980
Antonito2220041995
Gardner2220241998
Browns Park2120241992
Westcliffe2120241999
Wray Gulch1820231988
Powderhorn1820231995
Piedra1720241992
Guffey1620241991
Moffat1520241970
Como1520241996

Vesper Sparrow Population Trend in Other States

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

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.