The indigo bunting is a small bird, with a length of 11.5–13 cm (4.5–5 in). The male is a vibrant blue in the summer and a brown color during the winter months, while the female is brown year-round. The male displays brightly colored plumage during the breeding season to attract a mate. Nest-building and incubation are done solely by the female. The diet of the indigo bunting is insects during the summer months and seeds during the winter months.