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

Vesper Sparrow Population Trend in Montana

All statesGrassland birds

Vesper Sparrow in Montana has risen sharply: up 73% on the route-weighted index since 1970.

+73%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 →
105Routes 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 MontanaNotable 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 risen sharply in Montana: up 73% on the route-weighted index since 1970.

Vesper Sparrow Population Forecast in Montana

If the recent trend holds, Vesper Sparrow in Montana is projected to stay roughly flat through 2030, near 29 (95% range 18–39). A 5-year backtest shows a typical error of ±10.3%, with 100% of held-out values landing inside the 95% band.

-8%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 →
29Projected 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 →
18–3995% 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 →
±10.3%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 Montana is projected to stay roughly flat through 2030, near 29 (95% range 18–39). A 5-year backtest shows a typical error of ±10.3%, 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 →
2026281838
2027281839
2028281839
2029291839
2030291839

Vesper Sparrow Survey Routes in Montana

Routes recording Vesper Sparrow in Montana.
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 →
Leroy15720251970
Whitlash13220242009
Redstone12220251975
Custer 212220252024
Boulder11420251969
Shawmut10320251979
Westby10320252015
Custer9920222019
Freeman Creek8120162015
Beaverhead7520251973
Heart Butte7320252015
Roundup7220252016
Polson7020251972
Brusett6620241982
Wheat Basin6620252017
Augusta6420251976
Shelby6420252015
Sunburst6220071970
St Mary5720081972
St. Mary 25420252009
Fort Logan5420252018
Gildford5220252015
Willow Creek 25020251982
Muddy Creek4920152015
Winnett4620252017

Vesper Sparrow Population Trend in Other States

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

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