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Thrushes and Chats: Turdidae

Eastern Bluebird (sialia Sialis): Species Accounts

Physical characteristics: Eastern bluebirds have a length of 5.4 to 7.1 inches (13.9 to 17.8 centimeters). The adult male has a bright blue head and upperparts. Its throat, the sides of its neck, and its breast and flanks are colored orange, with a white belly. Females are duller blue with a crown and back that is gray in tone. Its eyes have white rings around them. Also in the female, the throat, breast, and sides are browner in color compared to the male's orange. Young birds tend to have gray-brown upperparts with white spotting on the back, as well as a brown chest with white scalloping, wings and tail that are blue in tint, with a white belly and undertail feathers.

Eastern bluebirds nest in tree cavities. If a female has a second set of chicks during the breeding season, the male takes care of the first set until they're ready to leave the nest. (Laura Riley/Bruce Coleman Inc. Reproduced by permission.)

Geographic range: The Eastern bluebird can be found in eastern North America, as far north as Hudson Bay, as far west as Arizona and the Rocky Mountains, and south to Bermuda, Florida, and central Mexico.

Habitat: The Eastern bluebird prefers the comforts of forest edges, open woodlands, farmland edges, or meadows, avoiding densely wooded or highly populated areas.

Diet: Eastern bluebirds are omnivores. In winter they eat fruit, particularly berries. Throughout the rest of the year they prefer eating insects, earthworms, snails, and other invertebrates.

Behavior and reproduction: Eastern bluebirds tend to group in pairs of families, and perch upright on exposed branches or at the tops of trees. In the winter they tend to be very sociable and form large flocks, roosting communally. They look for food on the ground, in foliage, or even in the air.

Eastern bluebirds tend to be monogamous, usually having two broods a year, and sometimes three. They nest in tree cavities, or holes—sometimes it might be in a cavity abandoned by a woodpecker. The female constructs the nest from dry grasses and weeds or pine needles, lining it with grass and sometimes with hair or fur. She lays three to six eggs that are mostly pale blue, though they can also be white. The female incubates the eggs for twelve to fourteen days. When the young are hatched, they are helpless, naked, and blind, and must stay in the nest where they are nourished and cared for by both parents. They grow their flight feathers about fifteen to twenty days after hatching, and remain in the nest for a few weeks after. If the female is preparing for the second brood, the male will take over the care of the young fledglings. In the case of the second brood, the young from the first also join in their care as well.

Eastern bluebirds and people: Eastern bluebirds tend to stay away from densely populated areas, and have no specific connection with humans.

Conservation status: Though no longer threatened as a species, some numbers were declining at the end of the twentieth century— up to 90 percent—due to the loss of nesting cavities, possibly due to the removal of dead trees and branches by humans, or in competition for nesting spots with house sparrows and European starlings. Efforts to stop the eastern bluebirds' decline, such as the introduction of nesting boxes, have helped significantly in many areas. ∎

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Animal Life ResourceBirdsThrushes and Chats: Turdidae - Physical Characteristics, Habitat, Diet, Behavior And Reproduction, Thrushes, Chats, And People - GEOGRAPHIC RANGE