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Adkins Arboretum Bluebird Research

Female Eastern Bluebird (Sialia sialis) in nest box

The male eastern bluebird, Sialia sialis, has a bright blue head, tail, back, and wings. The sides, flanks, and throat are chestnut red. The under parts are also chestnut red from the chin down to his white belly. The female has a light gray-blue head, dull brownish back, blue tail and wings, and a slight white ring around the eye.

Eastern bluebirds like to hunt their insect prey in short-cut grass with a few trees and fence posts scattered for perches. They eat a variety of invertebrates and also feed on wild fruits and berries, especially in winter.

The Arboretum’s meadows provide ideal nesting habitat for bluebirds. Bluebird trails and the use of man-made nest boxes have helped mitigate the effects of habitat loss and competition from exotic species, particularly house sparrows and European starlings. The Arboretum has maintained a bluebird trail of 23 boxes for several years. Boxes on the trail are cleaned by mid-March each year to be ready for the bluebirds that begin nesting in late March or early April.

The cup-shaped bluebird nest is usually made of grass, but sometimes pine needles or other small pieces of plant material are used. Bluebird eggs are light blue in color and occasionally white. Bluebird boxes are monitored every one to two weeks by a volunteer who looks not only for bluebird nests, eggs, and young but for signs of wasps, ants, blowfly larvae and nests of invasive house sparrows. Nests of beneficial native birds such as tree swallows and Carolina chickadees are left in the boxes until their young have fledged. Nests of invasive species are removed. Nesting boxes are cleaned after each brood fledges so that additional nests can be built for subsequent broods.

Enjoy watching bluebirds at the Arboretum all year long. Throughout the summer, bluebird families will stay together with juveniles from early broods sometimes helping with the care of younger broods. Look for them among the trees along the meadow. In winter, some bluebirds migrate to more southern latitudes, so the Arboretum may be host to bluebirds from the north who like Delmarva’s milder winters and its native plant food sources.

For more information, please visit The North American Bluebird Society or The Birdhouse Network.