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

Brewer's Sparrow Population Trend in Idaho

All statesGeneralists

Brewer's Sparrow in Idaho has edged down: down 13% on the route-weighted index since 1970.

-13%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 →
46Routes 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 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 stay roughly flat through 2029, near 15 (95% range 5.4–24). A 5-year backtest shows a typical error of ±30.8%, with 100% of held-out values landing inside the 95% band.

-10%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 →
15Projected 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 →
5.4–2495% 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 →
±30.8%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 stay roughly flat through 2029, near 15 (95% range 5.4–24). A 5-year backtest shows a typical error of ±30.8%, 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 →
2025155.524
2026155.424
2027155.424
2028155.424
2029155.424

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 →
Dubois7920241968
Lost River6920241985
Sawtooth Cty5220141988
Henry5019831973
Sawtooth City 24420242015
Tractor Flat3820241985
Magic Mtn3620241988
Kyle Canyon2120241985
Triangle2020241985
Challis1920241975
Iron Springs1720241988
Blackft Res1520181984
Crane Creek1520191988
Craters1420181979
Picabo1420211988
Almo1420231988
Glenns Ferry1219861985
Twin Buttes1120241985
Baker1120241974
Circular Bu920241985
Leadore820241974
Carey820181989
Cape Horn720241986
Bates720231988
Dougal Res720241988

Brewer's Sparrow Population Trend in Other States

arizonacaliforniacoloradokansasmontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwashingtonwyoming

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