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

Fox Sparrow Population Trend in Idaho

All statesGeneralists

Fox Sparrow in Idaho has surged: up 365% on the route-weighted index since 1977.

+365%Since 1977TrendPercent 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 →
33Routes 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 →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Fox 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 →

Fox Sparrow has surged in Idaho: up 365% on the route-weighted index since 1977.

Fox Sparrow Population Forecast in Idaho

If the recent trend holds, Fox Sparrow in Idaho is projected to fall about 21% by 2029 — from 1.7 in 2024 to a central estimate of 1.3 (95% range 0.44–2.2). A 5-year backtest shows a typical error of ±37.8%, with 60% of held-out values landing inside the 95% band.

-21%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 →
1.3Projected 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 →
0.44–2.295% 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 →
±37.8%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, Fox Sparrow in Idaho is projected to fall about 21% by 2029 — from 1.7 in 2024 to a central estimate of 1.3 (95% range 0.44–2.2). A 5-year backtest shows a typical error of ±37.8%, with 60% of held-out values landing inside the 95% band.19712029
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 →
20251.30.392.2
20261.30.402.2
20271.30.412.2
20281.30.432.2
20291.30.442.2

Fox Sparrow Survey Routes in Idaho

Routes recording Fox 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 →
Magic Mtn2420241992
Avery1120231979
Lolo Pass920191992
Challis820241977
Centerville820191982
Pierce720071994
Silver City520241993
Baldy Mountain320162013
Cascade219841983
Cape Horn220222021
Squirrel220051971
Yellow Pine220161990
Featherville220241990
Bates220051996
Sawtooth Cty220142011
Mivoden120181977
Grangeville120241986
Golden120141994
N Fork Cda R120032003
Leadore120042004
Rochat Divde120231993
Triangle120042004
Pocatello119921992
Coolin120241986
Sawtooth City 2120242015

Fox Sparrow Population Trend in Other States

alaskacaliforniacoloradomainemontananevadaoregonutahwashingtonwyoming

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