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

Vesper Sparrow Population Trend in Idaho

All statesGrassland birds

Vesper Sparrow in Idaho has surged: up 332% on the route-weighted index since 1970.

+332%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 →
50Routes 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 IdahoNotable 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 Idaho: up 332% on the route-weighted index since 1970.

Vesper Sparrow Population Forecast in Idaho

If the recent trend holds, Vesper Sparrow in Idaho is projected to rise about 11% by 2030 — from 9.1 in 2025 to a central estimate of 10 (95% range 2.9–17). A 5-year backtest shows a typical error of ±36.6%, with 100% of held-out values landing inside the 95% band.

+11%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 →
10Projected 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 →
2.9–1795% 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 →
±36.6%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 Idaho is projected to rise about 11% by 2030 — from 9.1 in 2025 to a central estimate of 10 (95% range 2.9–17). A 5-year backtest shows a typical error of ±36.6%, 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 →
2026102.817
2027102.917
2028102.917
2029102.917
2030102.917

Vesper Sparrow Survey Routes in Idaho

Routes recording Vesper Sparrow in Idaho.
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 →
Henry5919831976
Daniels Res5820251988
Sawtooth Cty4320141988
Carey3520251989
Iron Springs3120241988
Ririe2920251971
Blackft Res2620181984
Dubois2520251969
Sawtooth City 22520252015
Baker2220241974
Triangle1920251985
Almo1920251988
Cape Horn1420251972
Lost River1320251989
Magic Mtn1220251991
Craters1120181979
Dougal Res1120251988
Twin Buttes920251989
Challis920251976
Blacks Creek919891968
Tractor Flat920251985
Glenns Ferry819861986
Acequia820072002
Featherville720251990
Hot Spring620251988

Vesper Sparrow Population Trend in Other States

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

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