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

Chestnut-collared Longspur In Prairie Potholes

All regionsPrairie PotholesGrassland birds

Chestnut-collared Longspur in Prairie Potholes has fallen sharply: down 58% on the route-weighted index since 1969.

-58%Since 1969TrendPercent 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 →
64Routes 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 →
58YearsYears 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 declinecomputed 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 →

Chestnut-collared Longspur has fallen sharply in Prairie Potholes: down 58% on the route-weighted index since 1969.

Chestnut-collared Longspur In Prairie Potholes Population Forecast

If the recent trend holds, Chestnut-collared Longspur in Prairie Potholes is projected to fall about 49% by 2030 — from 5.5 in 2025 to a central estimate of 2.8 (95% range 0.00–8.2). A 5-year backtest shows a typical error of ±40.1%, with 100% of held-out values landing inside the 95% band.

-49%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 →
2.8Projected 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 →
0.00–8.295% 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 →
±40.1%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, Chestnut-collared Longspur in Prairie Potholes is projected to fall about 49% by 2030 — from 5.5 in 2025 to a central estimate of 2.8 (95% range 0.00–8.2). A 5-year backtest shows a typical error of ±40.1%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20263.50.008.9
20273.30.008.7
20283.10.008.6
20293.00.008.4
20302.80.008.2

Routes In Prairie Potholes

Routes recording Chestnut-collared 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 →
OswegoMONTANA712025
Ester LakeMONTANA562025
GlentanaMONTANA522025
ChinookMONTANA422025
SacoMONTANA382025
VirgelleMONTANA292025
SydneyNORTH-DAKOTA291983
WestbyMONTANA232025
ShelbyMONTANA192025
HarlemMONTANA152021
GlasgowMONTANA142024
CondeSOUTH-DAKOTA141984
Wild RoseNORTH-DAKOTA132025
RedstoneMONTANA122025
Danzig 2NORTH-DAKOTA112025
ForbesSOUTH-DAKOTA112012
Crow CreekSOUTH-DAKOTA102023
Long LakeSOUTH-DAKOTA92019
DenbighNORTH-DAKOTA82025
LambertMONTANA72025
Horsehead LkNORTH-DAKOTA72025
Sheyenne LkNORTH-DAKOTA62025
CooperstownNORTH-DAKOTA51994
GormanSOUTH-DAKOTA52010
WhitlashMONTANA42024

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