The Eastern Bluebird is among three bluebird species that belong to the thrush family. The other two are the Mountain Bluebird and the Western Bluebird.

Eastern Bluebirds live for about six years. They are social creatures and may gather in flocks of more than 100 birds.

Bluebirds prefer to nest in open fields, meadows, gardens, hedges and parks where trees are scattered and grasses short.

The population of Eastern Bluebirds was depleted in recent years by severe winter weather, pesticides used to control fire ants, development and competition from other cavity nesters. In North America, the Eastern Bluebird population has since rebounded, thanks to extensive installation of nesting boxes in rural areas.

Many Web sites explain how to build bluebird boxes. The North American Bluebird Society has a useful Web site: www.nabluebirdsociety.org.

An Eastern Bluebird’s nest is simple — made of grass and cup-shaped. The nest may take as little as two days or as long as two weeks to construct.

Eastern Bluebirds once were believed to be monogamous. Many scientists, however, have discovered that they no longer stick to one mate. The females may be socially monogamous, but they may mate with more than one male.

A female Eastern Bluebird may produce more than one brood in a breeding season. In that case, the first nest usually starts in the early part of spring; the second nest is started in the summer. Sometimes a young bluebird from the first brood will remain in the nest and assist its parents in caring for the second brood.

The female Eastern Bluebird lays four or five eggs. She usually will lay one egg each day, before noon. Not all eggs are blue; some may be white or gray. The female incubates her eggs for about two weeks. Once hatched, the young birds remain in the nest, cared for by both parents, for 15 to 20 days.