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

Vesper Sparrow Population Trend in Idaho

All statesGrassland birds

Vesper Sparrow in Idaho has surged: up 323% on the route-weighted index since 1970.

+323%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 →
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 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 323% 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 stay roughly flat through 2029, near 10 (95% range 3.1–18). A 5-year backtest shows a typical error of ±52.2%, with 100% of held-out values landing inside the 95% band.

-5%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 →
10Projected 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 →
3.1–1895% 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 →
±52.2%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 stay roughly flat through 2029, near 10 (95% range 3.1–18). A 5-year backtest shows a typical error of ±52.2%, 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 →
2025103.018
2026103.018
2027103.018
2028103.018
2029103.118

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
Dubois5820241969
Sawtooth Cty4320141988
Daniels Res4120191988
Iron Springs3120241988
Sawtooth City 22820242015
Blackft Res2620181984
Triangle2620241985
Baker2220241974
Twin Buttes2120241989
Picabo1620211988
Cape Horn1520241972
Challis1320241976
Lost River1220241989
Carey1220181989
Craters1120181979
Dougal Res1020241988
Almo1020231988
Blacks Creek919891968
Tractor Flat920241985
Glenns Ferry819861986
Acequia820072002
Featherville820241990
Squirrel620241971
Gifford519731973

Vesper Sparrow Population Trend in Other States

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

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