BirdAnalyst
Species · BCR 11 · BBS 2025 Release · 1966–2024

Chestnut-collared Longspur In Prairie Potholes

All regionsPrairie PotholesGeneralists

Chestnut-collared Longspur in Prairie Potholes has fallen sharply: down 56% on the route-weighted index since 1969.

-56%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 →
57YearsYears 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 56% 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 50% by 2029 — from 5.6 in 2024 to a central estimate of 2.8 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±33.8%, with 100% of held-out values landing inside the 95% band.

-50%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 →
2.8Projected 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 →
0.00–8.395% 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 →
±33.8%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, Chestnut-collared Longspur in Prairie Potholes is projected to fall about 50% by 2029 — from 5.6 in 2024 to a central estimate of 2.8 (95% range 0.00–8.3). A 5-year backtest shows a typical error of ±33.8%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20253.50.009.0
20263.30.008.8
20273.20.008.6
20283.00.008.5
20292.80.008.3

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 →
OswegoMONTANA772024
GlentanaMONTANA582024
Ester LakeMONTANA432024
ChinookMONTANA422024
VirgelleMONTANA352024
SydneyNORTH-DAKOTA291983
SacoMONTANA242024
ShelbyMONTANA232024
HarlemMONTANA152021
GlasgowMONTANA142024
CondeSOUTH-DAKOTA141984
LambertMONTANA132024
WestbyMONTANA122024
Horsehead LkNORTH-DAKOTA112024
ForbesSOUTH-DAKOTA112012
Crow CreekSOUTH-DAKOTA102023
Long LakeSOUTH-DAKOTA92019
Sheyenne LkNORTH-DAKOTA72024
Danzig 2NORTH-DAKOTA72024
ReganNORTH-DAKOTA62022
DenbighNORTH-DAKOTA62024
RedstoneMONTANA52024
CooperstownNORTH-DAKOTA51994
Powers LakeNORTH-DAKOTA52024
GormanSOUTH-DAKOTA52010

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.