Colorado State Bird - Lark Bunting

On April 29, 1931, the lark bunting was officially adopted as Colorado state bird, beating the western meadowlark and mountain bluebird for the title. The lark bunting, a medium-sized sparrow known for its striking black and white plumage during mating season, was chosen for its beauty, distinctiveness, and general fitting with the spirit of Colorado.

Identification

Known scientifically as Calamospiza melanocoryus, or colloquially as a prairie bobolink or white-winged blackbird, the lark bunting is a relatively easy bird to indentify in the field. Both males and females measure roughly six inches with a pale, finch-like beak. In mating season, males take on the appearance of formal wear, with a striking black body and crisp white wing patches.

The females and non-breeding males have a typical sparrow-like appearance, distinguished from similar species by the distinctive beak and white belly with heavy gray, brown and black streaks running lengthwise.

Habitat and Distribution

The lark bunting spends its summers in North American grasslands, from southern Alberta and Saskatchewan to the northern parts of Texas. During winter, birds form large flocks and migrate south to Mexico and parts of Texas and New Mexico.

Feeding

On both their wintering grounds and mating territory, the Colorado state bird typically forages on the ground for seeds, grains, insects, and occasionally for fruits. The bird strongly prefers open areas for feeding, avoiding sheltered places whenever possible. While most feeding is done on the ground, the lark bunting will sometimes engage in fly-catching behavior similar to a phoebe or kingbird, perching on a branch and then swooping out for a catch.

Mating

If there is one thing more distinctive about the lark bunting than its snappy plumage it is the male's courtship display, known as skylarking. Typically, a hopeful male will fly high up in the air, and then float softly downward while singing a complex series of whistles, chips and trills to gain the attention of the object of his desire.

Interestingly, recent research has suggested that female lark buntings change their mating selection criteria from year to year. For example, a female might one year select the male with the largest wing patches, and the next year choose the male with the smallest wing patches. Researchers speculate that this unusual behavior might allow the female to adapt her choice based on changes in nest predation and food availability, but no clear reason has been determined.

Once a mate has been selected, both partners engage in nesting activity. The nest is generally a simple, cupped depression scratched out on the ground, usually under low-lying branches or within the thicket of a shrub. Within the depression, the male and female build the nest of grass, stems and fine roots, lined with very fine grasses or bits of hair or fur.

The female lays a clutch of two to six pale blue eggs, and does most of the incubating while the male stands guard of the nest. After 12 days, the eggs hatch. Young lark buntings are altricial, meaning that they are mostly bald and helpless, therefore requiring a great deal of care from both parents.

Status of the Colorado State Bird

Population numbers for the lark bunting are known to fluctuate widely from year to year, however they do seem to be on an overall downward trend. Population surveys indicate that lark bunting populations have steadily declined at a rate of 2.5% per year in Colorado between 1966 and 2003. Currently, the lark bunting is listed as declining on the 'yellow' list of the United States Watch list, a joint project between the American Bird Conservancy and the National Audubon Society.

This is in keeping with a general trend for grassland birds as habitat is used up for human developments. As grasshoppers make up a significant portion of the lark bunting diet, the use of the pesticide diazinon is thought to play a role in the decline of the species.

If you happen to observe the lark bunting in your area, consider participating in one of the National Audubon's Citizen Science programs. You will be able to keep a record of your sightings, and help with population surveys at the same time.