According to the Cornell Lab of Ornithology, the Eastern bluebird has a big, rounded head, large eyes, and a short, straight bill for eating insects. The wings are long, but the tail and legs are fairly short, on a plump body. The male Eastern bluebird has bright feathers on his back and sides, with a rust-colored throat and breast. Females are gray colored with bluish wings and tails, and orange-brown breasts. Overall, the female has more subdued colors than the male.
Eastern Bluebirds prefer open country, where they perch on wires, posts, and low branches while looking for insects. In late fall and winter they will eat berries from trees and shrubs such as cedars, sumac, and dogwoods.
Bluebirds migrate south in late fall as their food supplies of insects and berries disappear, although a few may stay all winter if there is a good supply of berries. They return, looking for nesting sites in late February and March. Tree cavities and nesting boxes are most used for raising the 2 to 4 broods of young each year. The European Starling and house sparrow may compete for nesting sites.
The female lays about 4 to 5 blue eggs, although a few may be white. Eggs hatch in 14 days, and both parents feed the young insects for up to a week. In the nest, young bluebirds can be prey for snakes, feral cats, and raccoons. Starlings, house sparrows, and wrens also may smash eggs or kill young.
If the bluebirds survive their first few months after fledging, they may live two to three years. In the 1970's bluebird populations showed a sharp decline, probably due to the loss of habitat (open grassland with scattered trees and nesting cavities) and competition from other birds such as starlings and house sparrows. Bluebird populations have been increasing, based on the number of sightings in the annual Backyard Bird Count. This may be due to groups such as Bluebirds across Nebraska that are dedicated to helping the bluebird by providing nesting boxes and maintaining bluebird trails.
You can hear the call of a bluebird at Cornell Lab of Ornithology.