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

Field Sparrow Population Trend in Montana

All statesForest birds

Field Sparrow in Montana has surged: up 420% on the route-weighted index since 1979.

+420%Since 1979TrendPercent 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 →
32Routes 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 →
47YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Field 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 →

Field Sparrow has surged in Montana: up 420% on the route-weighted index since 1979.

Field Sparrow Population Forecast in Montana

If the recent trend holds, Field Sparrow in Montana is projected to fall about 28% by 2030 — from 2.0 in 2025 to a central estimate of 1.5 (95% range 0.64–2.3). A 5-year backtest shows a typical error of ±16.2%, with 100% of held-out values landing inside the 95% band.

-28%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 →
1.5Projected 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 →
0.64–2.395% 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 →
±16.2%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, Field Sparrow in Montana is projected to fall about 28% by 2030 — from 2.0 in 2025 to a central estimate of 1.5 (95% range 0.64–2.3). A 5-year backtest shows a typical error of ±16.2%, with 100% of held-out values landing inside the 95% band.19772030
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 →
20261.40.542.2
20271.40.572.2
20281.40.592.2
20291.40.622.2
20301.50.642.3

Field Sparrow Survey Routes in Montana

Routes recording Field 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 →
Hehn Draw3920252016
Savage2720251977
Miles City2320252015
Custer 22220252024
Custer2220222019
Jordan2120241982
Powderville2120251981
Cabin Creek1420252018
Forsyth1320231980
Brandenberg1020251979
Wolf Point1020242015
Leroy820252024
Lindsay720242015
Roy419911991
Virgelle219981998
Glen219851985
Circle220221997
Two Dot219771977
Webster219821982
Cleveland120241998
Harlem119981997
Glasgow120251979
Redstone120181986
Brusett120242011
Ingomar120162016

Field Sparrow Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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