The male indigo bunting is commonly seen as a breeding species and at migration hot spots. In the spring, the Indigo may be present in large flocks, particularly during migratory fallouts, and is often seen in brushy habitat or along weedy margins of fields and roads, where it sits up and twitches its tail. It sometimes hybridizes with the lazuli bunting. Monotypic. Length 5.5".
Highly sexually dimorphic. Summer male: plumage unmistakable, entirely bright blue. Winter male: blue obscured by brown and buff edging; mottled brown and blue early in winter. Summer female: dull brown, usually with 2 faint wing bars and indistinct streaking on underparts. Whitish throat, small conical bill with straight culmen, relatively long primary projection. Immature and winter female: more rufescent overall than breeding female, with blurry streaking on breast and flanks.
Males smaller than the male blue grosbeak, but lack chestnut wing bars, black on face, and dark streaks on back; also has smaller bill. Females similar to other female passerina buntings.
Call: a dry, metallic pik. Song: a series of sweet, varied phrases, usually paired.
Status and Distribution
Common. Breeding: found in brushy borders to mainly deciduous woodland throughout eastern United States. In the Southwest, mainly found in riparian habitats. Winter: mainly Mexico through Central America, rarely to northern South America. Also on Caribbean islands. Rare along Gulf Coast and southern Florida. Migration: mainly nocturnal. Arrives on breeding grounds mid-April–early June. In fall, mainly mid-September–mid-October. Vagrant: rare to Pacific states and Atlantic provinces.
Western birds may be limited by decrease in riparian habitats.
—From the National Geographic book Complete Birds of North America, 2006