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Species · Montana · BBS 2026 Release · 1966–2025

Thick-billed Longspur Population Trend in Montana

All statesGrassland birds

Thick-billed Longspur in Montana has surged: up 290% on the route-weighted index since 1970.

+290%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 →
36Routes 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 Thick-billed Longspur 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 →

Thick-billed Longspur has surged in Montana: up 290% on the route-weighted index since 1970.

Thick-billed Longspur Population Forecast in Montana

If the recent trend holds, Thick-billed Longspur in Montana is projected to fall about 43% by 2030 — from 5.7 in 2025 to a central estimate of 3.3 (95% range 0.66–5.9). A 5-year backtest shows a typical error of ±57.4%, with 20% of held-out values landing inside the 95% band.

-43%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 →
3.3Projected 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 →
0.66–5.995% 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 →
±57.4%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, Thick-billed Longspur in Montana is projected to fall about 43% by 2030 — from 5.7 in 2025 to a central estimate of 3.3 (95% range 0.66–5.9). A 5-year backtest shows a typical error of ±57.4%, with 20% 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 →
20263.10.525.8
20273.20.565.8
20283.20.595.8
20293.30.625.9
20303.30.665.9

Thick-billed Longspur Survey Routes in Montana

Routes recording Thick-billed Longspur 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 →
Maynard Coulee16820252017
Roundup10220252016
Whitlash6420242009
Virgelle5820251979
Gildford3220252015
Augusta3120251976
Shelby3020252016
Harlem2020211981
Glentana1820252015
Coleman Coulee1720242017
Dinosaurs H.M.1220252018
Oswego1020251978
Twin Bridges419761968
Hay Lake320251988
Glasgow320252004
Two Dot319811976
Heart Butte320252016
Sun River320172017
Wheat Basin320252017
St Mary219771968
Sunburst219871970
Malta219871980
Leroy220252025
Boulder219981969
Laurel219881988

Thick-billed Longspur Population Trend in Other States

coloradonebraskanorth-dakotawyoming

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