Photo by John Benson

© 2010 John Benson

Eastern Bluebird

Sialia sialis


The Eastern Bluebird is a small songbird. It has a plump body, long wings, and a short, straight bill. Males exhibit a bright blue color on the head, back, and wings, with a reddish-orange breast. Females’ colors are more muted, and they often exhibit gray rather than blue upperparts.


The Eastern Bluebird averages 7” (18 cm) in length and 1 ounce (30 g) in weight.


  • The Eastern Bluebird’s short, straight bill is well-suited to pecking at the ground for insects and eating winter berries.
  • Bluebirds have excellent eyesight, and can see an insect from 60 feet away!
  • The dull grayish coloring of a female bluebird helps it to camouflage while sitting on its nest.


During the warmer months, bluebirds consume insects which they find on or near the ground. In the winter, when insects cannot be found, their diets change and they primarily consume berries. At Cosley Zoo, the bluebird and other songbirds are fed a commercial avian diet, birdseed, fruits and vegetables, crickets, and mealworms.


Bluebirds nest in natural cavities (such as woodpecker holes in trees), or in nest boxes humans have installed to attract the birds. The male attracts the female to his nest site, where she builds the nest. Females lay 3-7 pale blue (or occasionally white) eggs per clutch (group of eggs), and they incubate the eggs for 13-16 days before they hatch. A pair of bluebirds will often stay together through several mating seasons, and can raise 2-3 broods (groups of young) per year.

Shelter and Space Needs

Bluebirds prefer areas with ample open space, and are commonly found on farms and roadsides, and in backyards and parks. Eastern Bluebirds are common throughout Illinois. Bluebirds which summer in northern Illinois typically migrate further south during the winter months.

Life Expectancy

The oldest known Eastern Bluebird lived 10 years and 5 months, although most live only a few years.

Relationship With Man

This species is popular with birdwatchers, who often erect nest boxes to attract these lovely birds. Although bluebird populations were in decline in the early 20th century, the species has made a comeback, with numbers increasing in recent decades. This comeback is thought to be due to conservation efforts which involved erecting nest boxes for the birds.

Fun Facts

  • The bluebird is thought to be a symbol of happiness in many cultures worldwide and has often been mentioned in American popular songs, including “Zip-a-Dee-Doo-Dah,” “Blue Skies,” and “Birdhouse in Your Soul.”
  • A male bluebird singing to attract a mate may sing up to 1,000 songs per hour.


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