Lark Bunting

The Lark Bunting is a striking, highly social sparrow-relative of the North American Great Plains, notable for one of the most dramatic examples of seasonal plumage change among American songbirds. It is the official state bird of Colorado.

Breeding males are essentially entirely black except for a large, bold white patch on the wing, an unmistakable combination among grassland songbirds. Females and nonbreeding males, by contrast, are streaky grayish-brown overall, more typical of a sparrow, though they retain a smaller version of the same white wing patch, a useful clue even in dull plumage.

Outside the breeding season, Lark Buntings become highly gregarious, forming large, often mixed flocks that move nomadically across the plains and wintering grounds in response to food availability.

Key Field Marks

• Breeding male: entirely black body with a large white patch on the wing
• Female and nonbreeding male: streaky grayish-brown overall, sparrow-like, with a smaller white wing patch
• Relatively large, conical, pale-based bill
• Large size and bulky build compared to most sparrows

Similar Species

Breeding males are unmistakable due to their solid black body and white wing patch, a combination shared by no other North American sparrow-like bird. Females and winter males can resemble other streaky sparrows but the white wing patch, even when reduced, is a useful distinguishing mark, along with the bird's characteristically heavy bill and gregarious flocking behavior.

Lark Buntings breed across the shortgrass and mixed-grass prairie of the Great Plains, from southern Canada south through Montana, the Dakotas, Nebraska, Kansas, Colorado, and into New Mexico and Texas, often in areas with scattered low shrubs such as sagebrush or greasewood.

In winter, the species withdraws to the southwestern United States and Mexico, where large flocks forage in open grassland, agricultural fields, and desert scrub. The species is highly nomadic, and its breeding distribution can shift substantially from year to year depending on rainfall and grassland conditions.

Behavior

Outside the breeding season, Lark Buntings are strongly gregarious, forming large flocks, sometimes numbering in the hundreds, that move together across open country in search of food.

Voice

Males deliver a rich, varied, warbling song, often performed during a skylarking flight display in which the bird flutters upward on shallow wingbeats and glides back down while singing.

Feeding

Diet shifts seasonally: insects dominate during the breeding season, especially for feeding nestlings, while seeds and waste grain become the primary food in fall and winter.

Nesting and Breeding

Nests are built on the ground, typically at the base of a grass clump or small shrub, as a woven cup of grasses. Clutches usually contain 3-5 pale blue eggs, and the species can be locally polygynous, with some males mating with more than one female.