BirdAnalyst
Species · BCR 11 · BBS 2026 Release · 1966–2025

Thick-billed Longspur In Prairie Potholes

All regionsPrairie PotholesGrassland birds

Thick-billed Longspur in Prairie Potholes has surged: up 422% on the route-weighted index since 1972.

+422%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 →
16Routes 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 →
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 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 surged in Prairie Potholes: up 422% on the route-weighted index since 1972.

Thick-billed Longspur In Prairie Potholes Population Forecast

If the recent trend holds, Thick-billed Longspur in Prairie Potholes is projected to fall about 26% by 2030 — from 2.1 in 2025 to a central estimate of 1.6 (95% range 0.35–2.8). A 5-year backtest shows a typical error of ±36.8%, with 80% of held-out values landing inside the 95% band.

-26%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 →
1.6Projected 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 →
0.35–2.895% 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 →
±36.8%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 Prairie Potholes is projected to fall about 26% by 2030 — from 2.1 in 2025 to a central estimate of 1.6 (95% range 0.35–2.8). A 5-year backtest shows a typical error of ±36.8%, with 80% of held-out values landing inside the 95% band.19702030
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 →
20261.50.252.7
20271.50.282.7
20281.50.302.7
20291.50.322.7
20301.60.352.8

Routes In Prairie Potholes

Routes recording Thick-billed Longspur in Prairie Potholes.
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 →
WhitlashMONTANA642024
VirgelleMONTANA582025
GildfordMONTANA322025
ShelbyMONTANA302025
HarlemMONTANA202021
GlentanaMONTANA182025
OswegoMONTANA102025
Hay LakeMONTANA32025
GlasgowMONTANA32025
Sun RiverMONTANA32017
SunburstMONTANA21987
MaltaMONTANA21987
ChinookMONTANA22025
ClevelandMONTANA11979
RedstoneMONTANA12018
Great FallsMONTANA12004

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