Eastern Bluebird
(Sialia sialis)
Eastern Bluebird by Sean Maloney DNR Photo Contest Submission
Description & Range:
Eastern bluebirds are small birds in the thrush family measuring 6-8 inches long. They have round, plump bodies and round heads with short, straight beaks. Their wingspan is about 10 to 13 inches. Adult males have vivid blue backs, rusty coloring on their throat and breast, and white bellies. Adult females are grayish-blue with a more subdued orange-brown breast.
The range of the eastern bluebird is widespread, extending east of the Rockies all the way from Canada to Latin America.
Habitat:
Eastern bluebirds live in open areas with scattered trees, such as farms, roadsides, forest clearings, and suburban parks, backyards, and golf courses. They build their nests in old woodpecker holes in dead pine or oak trees, up to 50 feet off the ground. They will also commonly build their nests in nest boxes or other artificial dwellings.
Diet:
Most of the year, eastern bluebirds will eat ground-dwelling insects such as caterpillars, beetles, crickets, spiders, and grasshoppers. During the colder months they will eat more berries, such as blueberries, sumac, black cherry, currants, wild holly, dogwood, hackberries, pokeweed, juniper berries, and more.
Reproduction:
Males attract females to their nest with a display of carrying bits of nesting material into and out of the nest. Once pair-bonded, bluebirds mate for several seasons and produce two to three broods each year. Each time, the female lays between 3 and 7 eggs, which she then incubates for 13 to 16 days. The fledglings will leave the nest after about 3 weeks.
Sounds:
The most common call of the eastern bluebird is a soft, low-pitched tu-a-wee sound that lasts less than a second. They use this call to keep in touch with each other or signal to their young that they are bringing food. They also have a low-pitched, warbling song made of several phrases with 1-3 short notes, lasting a total of 2 seconds. Males will sing this song to attract a mate, while females may sing it when predators are nearby. Females also use song to communicate with their mate.
Behavior:
Eastern bluebirds will perch on wires, posts, and branches while they scan the area for prey, which they can spot from over 60 feet away. Once spotted, they’ll dive down from above to grab their prey. They fly fast and low to the ground, with an irregular wingbeat pattern. Eastern bluebirds are often in competition for nesting sites with house sparrows, European starlings, tree swallows, Carolina chickadees, and several other species. When competing for nesting locations or territory, males will chase each other at high speeds while grappling with their feet and pulling at feathers with their beaks.
Conservation:
By the 1950s and 1960s, eastern bluebird populations dropped dramatically and were nearly eliminated from Maryland. The steep decline in population was caused by a number of factors, including less available habitat, competition for nesting sites with non-native species like the house sparrow, and the effects of pesticides like DDT. The ban of DDT and erection of bluebird nesting boxes helped their population rebound dramatically, and is now considered stable. The continued establishment of nest boxes and volunteer monitoring programs has helped contribute to their success.
Sources:
https://www.chesapeakebay.net/discover/field-guide/entry/eastern-bluebird
https://dnr.maryland.gov/parkquest/Documents/PQ_BigRun.pdf
https://www.audubon.org/field-guide/bird/eastern-bluebird
https://www.allaboutbirds.org/guide/Eastern_Bluebird/id
