BirdAnalyst
Species · South Dakota · BBS 2025 Release · 1966–2024

Chestnut-collared Longspur Population Trend in South Dakota

All statesGeneralists

Chestnut-collared Longspur in South Dakota has collapsed: down 77% on the route-weighted index since 1969.

-77%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 →
43Routes 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 →
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 Chestnut-collared Longspur Trends in South DakotaNotable 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 collapsed in South Dakota: down 77% on the route-weighted index since 1969.

Chestnut-collared Longspur Population Forecast in South Dakota

If the recent trend holds, Chestnut-collared Longspur in South Dakota is projected to fall about 100% by 2029 — from 6.5 in 2024 to a central estimate of 0.00 (95% range 0.00–15). A 5-year backtest shows a typical error of ±326.9%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1595% 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 →
±326.9%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 South Dakota is projected to fall about 100% by 2029 — from 6.5 in 2024 to a central estimate of 0.00 (95% range 0.00–15). A 5-year backtest shows a typical error of ±326.9%, 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 →
20250.000.0015
20260.000.0015
20270.000.0015
20280.000.0015
20290.000.0015

Chestnut-collared Longspur Survey Routes in South Dakota

Routes recording Chestnut-collared Longspur in South Dakota.
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 →
Lodgepole9420241990
Reva4020241979
Conde1419841967
Forbes1120121967
Crow Creek1020231967
Long Lake920191967
Maurine820241968
Chamberlain720101967
Ft Thompson620111967
Gorman520101979
Harding420141967
Lacreek420141995
Britton319851973
Ottumwa320181967
Cedar Pass319841969
Pioneer220121997
Rosebud220101967
Raymond219851967
Lane219781967
Wilmot219701970
Veblen219781969
Promise220091986
Volunteer220031967
Isabel220151990
S. Pioneer220221994

Chestnut-collared Longspur Population Trend in Other States

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