Eastern Bluebird

Eastern Bluebirds are a thrush species and cousin to the American Robin. They are recognized by their bubbly song, blue head, wings, and tail, and red-orange breast. 

Only seven inches long, the bluebird is much smaller than its noisy blue and white woodland neighbor, the blue jay (12 inches) but larger than the all blue, shrubnesting indigo bunting (five inches). Also, bluebirds eat, behave and nest differently from our western Iowa blue grosbeak (seven inches).

Nesting & Family

They are often found in open woodlands, savannas, golf courses, and parks or on fence posts and telephone lines along country roads. They nest in cavities (aka holes) in trees, but cannot build their own so they rely on other species like woodpeckers to build and abandon holes in dead trees or on humans to build and maintain bluebird nest boxes. 

They often nest more than once each summer, laying a clutch of 2-7 pale blue eggs. Species like native tree swallows and invasive non-native species like house sparrows often compete for use of bluebird nest boxes. 

Unfortunately, this species is declining in many midwestern states, including Iowa. 

Habitat & Diet

Eastern Bluebirds eat insects and berries, often swooping to the ground to find prey. They may come to feeders, but only if fruit or mealworms are available. 

Eastern Bluebirds are migratory and many of the birds we see in Iowa during the summer move to the Southeastern US during winter, though smaller numbers of bluebirds can be found in Iowa all year.

Common Threats

• Raccoons live in the same forest edge areas and can climb almost any post or tree that supports a bluebird nest. With dexterous paws, they can even undo latches! Raccoon attacks increase through the breeding season, affecting second and third nests most. 
• Cats are also a serious and cunning predator of bluebirds. Nest boxes should be placed at least 100 yards from buildings, to avoid both marauding cats and house sparrows. 
• Starlings and house sparrows are cavity nesting birds imported from Europe during the late 1800s. They are extremely adaptable and compete strongly with bluebirds and other cavity dwellers for available nest sites. Since these bird pests are more common near buildings, keep bluebird boxes at least 100 yards away from human structures. 
• House wrens compete with bluebirds for nest sites. They will fill boxes with twigs, covering over bluebird nests. More importantly, wrens peck or throw out bluebird eggs in an effort to drive away the bluebirds. Place bluebird boxes in the open, facing away from brush to reduce this lethal competition.
• Blowflies can be deadly parasites of young bluebirds. These fly larvae build up through the nesting season and attack later broods most heavily. Good nest box sanitation (fresh air, sunlight) between nestlings and at the end of the season are the best defenses. 

Supporting the Eastern Bluebird

You can reduce this competition, by placing boxes in pairs, one for the bluebirds, and one for the swallows. 

To learn more about how to host a bluebird nest box, check out our bluebird brochure or the North American Bluebird Society website for resources.