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

Thick-billed Longspur Population Trend in Colorado

All statesGeneralists

Thick-billed Longspur in Colorado has risen sharply: up 60% on the route-weighted index since 1972.

+60%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 →
12Routes 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 →
54YearsYears 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 →

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 risen sharply in Colorado: up 60% on the route-weighted index since 1972.

Thick-billed Longspur Population Forecast in Colorado

If the recent trend holds, Thick-billed Longspur in Colorado is projected to rise about 52% by 2029 — from 0.96 in 2024 to a central estimate of 1.5 (95% range 0.35–2.6). A 5-year backtest shows a typical error of ±97%, with 100% of held-out values landing inside the 95% band.

+52%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 →
1.5Projected 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 →
0.35–2.695% 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 →
±97%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 52% by 2029 — from 0.96 in 2024 to a central estimate of 1.5 (95% range 0.35–2.6). A 5-year backtest shows a typical error of ±97%, 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 →
20251.40.282.5
20261.40.302.5
20271.40.322.5
20281.40.342.5
20291.50.352.6

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
Nunn2020211995
Grover1720241992
Briggsdale820071969
Adams Co.220162015
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 2026-05-22.