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Species · Colorado · BBS 2026 Release · 1966–2025

Thick-billed Longspur Population Trend in Colorado

All statesGrassland birds

Thick-billed Longspur in Colorado has increased: up 41% on the route-weighted index since 1972.

+41%Since 1972TrendPercent 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 →
13Routes 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 →
55YearsYears 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 ColoradoNotable 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 Thick-billed Longspur in Colorado. See the full index history below.

Thick-billed Longspur Population Forecast in Colorado

If the recent trend holds, Thick-billed Longspur in Colorado is projected to rise about 191% by 2030 — from 0.48 in 2025 to a central estimate of 1.4 (95% range 0.28–2.5). A 5-year backtest shows a typical error of ±122.3%, with 80% of held-out values landing inside the 95% band.

+191%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 →
1.4Projected 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 →
0.28–2.595% 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 →
±122.3%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 Colorado is projected to rise about 191% by 2030 — from 0.48 in 2025 to a central estimate of 1.4 (95% range 0.28–2.5). A 5-year backtest shows a typical error of ±122.3%, with 80% of held-out values landing inside the 95% band.19692030
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 →
20261.30.222.5
20271.40.232.5
20281.40.252.5
20291.40.262.5
20301.40.282.5

Thick-billed Longspur Survey Routes in Colorado

Routes recording Thick-billed Longspur in Colorado.
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 →
Rockport7520241994
Nunn4920251995
Grover1720241992
Adams Co.220162015
Last Chance 2220252025
Briggsdale120251969
Arsenal 2120222022
Gordon Creek120181992
Stoneham120211992
Crowley119971997
Rush120241992
Limon120222016
Ellicott119991999

Thick-billed Longspur Population Trend in Other States

montananebraskanorth-dakotawyoming

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