BirdAnalyst
Species · BCR 16 · BBS 2026 Release · 1966–2025

Thick-billed Longspur In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauGrassland birds

Thick-billed Longspur in Southern Rockies / Colorado Plateau has risen sharply: up 74% on the route-weighted index since 1980.

+74%Since 1980TrendPercent 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 →
3Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
18YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 Southern Rockies / Colorado Plateau: up 74% on the route-weighted index since 1980.

Thick-billed Longspur In Southern Rockies / Colorado Plateau Population Forecast

If the recent trend holds, Thick-billed Longspur in Southern Rockies / Colorado Plateau is projected to fall about 21% by 2030 — from 0.14 in 2025 to a central estimate of 0.11 (95% range 0.01–0.20). A 5-year backtest shows a typical error of ±54.6%, with 60% of held-out values landing inside the 95% band.

-21%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 →
0.11Projected 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 →
0.01–0.2095% 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 →
±54.6%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 Southern Rockies / Colorado Plateau is projected to fall about 21% by 2030 — from 0.14 in 2025 to a central estimate of 0.11 (95% range 0.01–0.20). A 5-year backtest shows a typical error of ±54.6%, with 60% of held-out values landing inside the 95% band.19782030
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 →
20260.100.000.20
20270.100.000.20
20280.100.010.20
20290.100.010.20
20300.110.010.20

Routes In Southern Rockies / Colorado Plateau

Routes recording Thick-billed Longspur in Southern Rockies / Colorado Plateau.
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 →
BufordWYOMING182025
Sybille CynWYOMING22025
Fletcher PkWYOMING12024

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