There are three species of these colorful North American birds. Eastern and western bluebirds have a reddish brown breast, which contrasts with their predominately blue plumage. Their relative, the (male) mountain bluebird is entirely blue.
Eastern bluebirds are primarily found east of the Rockies, and range from Canada to Mexico and Honduras. They are much admired for their lovely coloring and for a distinctive song that many hear as "chur-lee, chur-lee." The eastern bluebird is the state bird of both New York and Missouri.
Western bluebirds are found west of the Rocky Mountains from Canada to Mexico. The mountain bluebird also inhabits much of western North America—often at elevations above 7,000 feet (2,133 meters).
Bluebirds eat small fruits and hunt insects, spiders, and other creatures from above. The birds perch, watch, and then swoop to the ground to pounce on their prey.
Pairs mate in spring and summer, when they construct small, bowl-shaped nests. Females lay four or five eggs and incubate them for about two weeks. Young remain in the nest, cared for by both parents, for an additional 15 to 20 days. Bluebirds often have two broods in a season. Sometimes, a young bluebird from the first brood will remain in the nest and assist its parents in caring for the second.
Bluebirds living in higher latitudes may head south if food becomes scarce or temperatures too cold. Mountain bluebirds typically migrate to lower elevations during the same lean seasons.
Bluebirds are considered fairly common, but their numbers have declined substantially during the last century. Populations have been given a boost by the birdhouse boxes that have become popular in many parks and backyards.