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.
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.