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

Fox Sparrow Population Trend in Montana

All statesGeneralists

Fox Sparrow in Montana has surged: up 232% on the route-weighted index since 1971.

+232%Since 1971TrendPercent 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 →
22Routes 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 →
50YearsYears 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 MontanaNotable 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 Montana: up 232% on the route-weighted index since 1971.

Fox Sparrow Population Forecast in Montana

If the recent trend holds, Fox Sparrow in Montana is projected to fall about 18% by 2029 — from 0.67 in 2024 to a central estimate of 0.55 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±21%, with 100% of held-out values landing inside the 95% band.

-18%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 →
0.55Projected 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 →
0.00–1.195% 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 →
±21%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 Montana is projected to fall about 18% by 2029 — from 0.67 in 2024 to a central estimate of 0.55 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±21%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.530.001.1
20260.540.001.1
20270.540.001.1
20280.540.001.1
20290.550.001.1

Fox Sparrow Survey Routes in Montana

Routes recording Fox Sparrow in Montana.
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 →
Logan Pass2020241980
Whitefish Lake1720242016
Inside Road420241990
Fish Creek420242022
Hebgen Lake420242019
Chestnut320091999
Libby Dam220241984
Woodman220241969
Sula220241977
Noxon220112011
St Mary119891989
Pryor Mtn.120182001
St Regis120242002
Arlee120241970
Clinton120012001
Elliston119741974
East Glacier Park120222015
Red Rock119891989
Skalkho-Rye120102000
Swan Lake120212017
Ninemile120181999
Painted Rock120192015

Fox Sparrow Population Trend in Other States

alaskacaliforniacoloradoidahomainenevadaoregonutahwashingtonwyoming

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