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

Brewer's Sparrow Population Trend in Idaho

All statesArid-land birds

Brewer's Sparrow in Idaho has edged down: down 20% on the route-weighted index since 1970.

-20%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 →
47Routes 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 Brewer's 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 →

No notable trend signals for Brewer's Sparrow in Idaho. See the full index history below.

Brewer's Sparrow Population Forecast in Idaho

If the recent trend holds, Brewer's Sparrow in Idaho is projected to rise about 13% by 2030 — from 13 in 2025 to a central estimate of 14 (95% range 5.0–24). A 5-year backtest shows a typical error of ±22.2%, with 100% of held-out values landing inside the 95% band.

+13%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 →
14Projected 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 →
5.0–2495% 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 →
±22.2%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, Brewer's Sparrow in Idaho is projected to rise about 13% by 2030 — from 13 in 2025 to a central estimate of 14 (95% range 5.0–24). A 5-year backtest shows a typical error of ±22.2%, 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 →
2026145.124
2027145.024
2028145.024
2029145.024
2030145.024

Brewer's Sparrow Survey Routes in Idaho

Routes recording Brewer's 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 →
Dubois5820251968
Sawtooth Cty5220141988
Tractor Flat5120251985
Henry5019831973
Sawtooth City 25020252015
Almo4220251988
Lost River4120251985
Twin Buttes2820251985
Magic Mtn2620251988
Daniels Res2320251988
Hot Spring2120251988
Challis1720251975
Iron Springs1720241988
Blackft Res1520181984
Circular Bu1520251985
Crane Creek1520191988
Craters1420181979
Triangle1420251985
Kyle Canyon1220251985
Glenns Ferry1219861985
Baker1120241974
Leadore820241974
Cape Horn720251986
Carey720251989
Bates720231988

Brewer's Sparrow Population Trend in Other States

arizonacaliforniacoloradokansasmontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwashingtonwyoming

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