The bluebirds are a group of medium-sized, mostly insectivorous or omnivorous birds in the genus Sialia of the thrush family (Turdidae). Bluebirds are one of the few thrush genera in the Americas. They have blue, or blue and red, plumage. Female birds are less brightly colored than males, although color patterns are similar and there is no noticeable difference in size between sexes.
Bluebirds are territorial, prefer open grassland with scattered trees and are cavity nesters (similar to many species of woodpecker). Bluebirds can typically produce between two and four broods during the spring and summer (March through August in the Northeastern United States). Males identify potential nest sites and try to attract prospective female mates to those nesting sites with special behaviors that include singing and flapping wings, and then placing some material in a nesting box or cavity. If the female accepts the male and the nesting site, she alone builds the nest and incubates the eggs.
Predators of young bluebirds in the nests can include snakes, cats and raccoons. Non-native and native bird species competing with bluebirds for nesting locations include the Common Starling, American Crow, and House Sparrow, which take over the nesting sites of bluebirds, killing young and smashing eggs and probably killing adult bluebirds.