bluebird, common name for a North American migratory bird of the family Turdidae (thrush family). The eastern bluebird, Sialia sialis, is among the first spring arrivals in the North. It is about 7 in. (17.8 cm) long. The plumage of the male appears vivid blue in bright light and black at a distance; the breast is cinnamon-red, the under parts white. The female's coloring is duller. The bluebird usually nests in orchards or on the edges of woodlands but will also use nesting boxes. As a destroyer of insects it is of great value; it also eats wild fruits. Related birds are the mountain, the western (genus Sialia) or chestnut-backed, and the Florida bluebirds. Bluebirds have a cheerful call and a sweet, warbling song. They raise several broods during a single mating season. The female is responsible for the incubation duties. Bluebirds are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Passeriformes, family Turdidae.

Any of three North American bird species (songbird genus Sialia) of the chat-thrush group. The eastern bluebird (S. sialis), which is 5.5 in. (14 cm) long, and the western bluebird (S. mexicana) are red-breasted forms found east and west of the Rockies, respectively. The mountain bluebird (S. currucoides), also found in the West, is all blue. Bluebirds arrive from the south in earliest spring. They live in open country and woodlands and nest in holes in trees or in fence posts and bird boxes.

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