BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Lark Bunting

PasserellidaeGrassland birdsCalamospiza melanocorys

Lark Bunting has fallen sharply: down 70% on the route-weighted index since 1969.

-70%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 →
553RoutesSurvey 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 Lark Bunting

The Lark Bunting (Calamospiza melanocorys) is a North American member of the New World Sparrows (Passerellidae). In this analysis it is grouped with the grassland birds.

Size
4.5–7.5 in long (12–19 cm) — a small 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 553 Breeding Bird Survey routes across 17 states, most concentrated in the Badlands and Prairies.
Family
Passerellidae · Grassland birds

Notable Lark Bunting 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 →

Lark Bunting has fallen sharply in surveyed states: down 70% on the route-weighted index since 1969.

Lark Bunting Population Forecast

If the recent trend holds, Lark Bunting is projected to fall about 13% by 2029 — from 2.7 in 2024 to a central estimate of 2.4 (95% range 0.00–5.1). A 5-year backtest shows a typical error of ±26.4%, with 100% of held-out values landing inside the 95% band.

-13%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 →
2.4Projected 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 →
0.00–5.195% 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 →
±26.4%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, Lark Bunting is projected to fall about 13% by 2029 — from 2.7 in 2024 to a central estimate of 2.4 (95% range 0.00–5.1). A 5-year backtest shows a typical error of ±26.4%, 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 →
20252.70.005.5
20262.60.005.4
20272.50.005.3
20282.40.005.2
20292.40.005.1

Where the Lark Bunting Is Detected

BBS routes recording Lark Bunting, sized by most recent count.

Lark Bunting Population Trend by State

Lark Bunting 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 →
Arizonainsufficient datan/a2
Californiainsufficient datan/a1
Colorado-86%197078
Idaho-96%199611
Iowainsufficient datan/a3
Kansas-97%196931
Minnesotainsufficient datan/a3
Missouriinsufficient datan/a1
Montana-69%197066
Nebraska-74%196954
New Mexico-67%197028
North Dakota-99%196942
Oklahoma+53%196910
South Dakota-83%196954
Texas+357%196931
Utah-93%199622
Wyoming-69%1970116

Lark Bunting Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Lark Bunting 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 →
Great Basin-64%199519
Northern Rockies-34%197083
Prairie Potholes-89%196974
Southern Rockies / Colorado Plateau-98%197045
Badlands and Prairies-79%1969126
Shortgrass Prairie-73%1969124
Central Mixed Grass Prairie-95%196963
Chihuahuan Desert-78%19738

Lark Bunting Conservation Status

Our route-weighted index shows it down about 70% 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.