BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Chestnut-collared Longspur

CalcariidaeGrassland birdsCalcarius ornatus

Chestnut-collared Longspur has fallen sharply: down 68% on the route-weighted index since 1969.

-68%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 →
164RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Chestnut-collared Longspur

The Chestnut-collared Longspur (Calcarius ornatus) is a North American member of the Longspurs & Snow Buntings (Calcariidae). In this analysis it is grouped with the grassland birds.

Size
5.5–7 in long (14–18 cm) — a small ground songbird (typical for the family)
Habitat
Open grasslands, prairie, pasture and hayfields.
Diet
Seeds and insects gathered from grasses and the ground.
Range
Recorded on 164 Breeding Bird Survey routes across 7 states, most concentrated in the Badlands and Prairies.
Family
Calcariidae · Grassland birds

Notable Chestnut-collared Longspur TrendsNotable 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 surveyed states: down 68% on the route-weighted index since 1969.

Chestnut-collared Longspur Population Forecast

If the recent trend holds, Chestnut-collared Longspur is projected to fall about 100% by 2029 — from 0.43 in 2024 to a central estimate of 0.00 (95% range 0.00–0.42). A 5-year backtest shows a typical error of ±104.6%, with 40% 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 →
0.00–0.4295% 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 →
±104.6%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, Chestnut-collared Longspur is projected to fall about 100% by 2029 — from 0.43 in 2024 to a central estimate of 0.00 (95% range 0.00–0.42). A 5-year backtest shows a typical error of ±104.6%, with 40% 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 →
20250.040.000.46
20260.030.000.45
20270.010.000.43
20280.000.000.42
20290.000.000.42

Where the Chestnut-collared Longspur Is Detected

BBS routes recording Chestnut-collared Longspur, sized by most recent count.

Chestnut-collared Longspur Population Trend by State

Chestnut-collared Longspur population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Colorado-95%197712
Minnesotainsufficient datan/a1
Montana+66%197045
Nebraska-96%19697
North Dakota-82%196940
South Dakota-77%196943
Wyoming-80%198116

Chestnut-collared Longspur Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Chestnut-collared Longspur population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Rockies-87%19718
Prairie Potholes-56%196964
Badlands and Prairies-77%196974
Shortgrass Prairie-92%196916

Chestnut-collared Longspur Conservation Status

Our route-weighted index shows it down about 68% since 1969. Grassland birds are North America's steepest-declining group, down roughly 50% since 1970 as prairie and pasture were lost.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.