Eastern Bluebird
Scientific Name: Sialia sialis
Classification: Nongame Species
Abundance: Statewide
The male Eastern bluebird has bright blue upper parts, a rusty throat, breast and sides, and a white belly. The female’s coloring is similar, but duller. The bluebird’s average length is 7 inches. Eastern bluebirds prefer open or semi-open habitats with grassy areas and nearby woods. Farmyards, groves and even some residential areas provide suitable habitat. Bluebirds perch on trees, posts, power lines and fences to search for insects, dropping to the ground to capture their prey. Occasionally they catch an insect in the air. Bluebirds eat insects, snails, spiders and earthworms. They supplement their diet with berries, eating the fruits of plants such as viburnums, dogwoods, and black and pin cherry in the summer and fall. In the winter, they eat berries of sumac, pyracantha, mistletoe, bayberry and American holly. During winter, bluebirds roost in small flocks in woodlands or sometimes huddle in nesting cavities to keep warm. They must eat constantly during the day to survive cold nights.
The bluebird’s main predators are raccoons, cats, opossums and snakes. Members of the thrush family, bluebirds compete for nesting sites with other birds such as the house sparrow, the Carolina chickadee and the white-breasted nuthatch. During spring and summer, other birds raid bluebird nests for eggs and a place to raise their young. Bluebirds, too, may banish chickadees and other species from their nests.
Once a male finds a suitable site, he flutters and sings “churwee, chur-wee” to attract his mate for the season. Once she arrives, she must accept the site. If she does, both the male and female build a neat cup of dry grasses or pine needles. Nest building takes about 10 days.
After the young have hatched, the mother bluebird stays in the nest for the first few days to keep her young warm, and the male feeds them. Later, both parents feed the nestlings with soft insects, then coarser foods as they grow. The young grow quickly, leaving the nest 17 to 18 days after hatching. The parents care for the young and teach them how to catch their own food. The male takes over this job when the female begins her next nest. Bluebirds can raise two or three broods of young each year if not disturbed by predators. Young bluebirds from the first brood may stay and help with subsequent broods.
The eastern bluebird is a nongame species with no open hunting season. Like other songbirds, bluebirds are federally protected under the Migratory Bird Treat Act. Because they are federally protected, it is illegal to harm them, their nests or their eggs.
A small bird keeps hitting my window!
Male songbirds will sometimes mistake their reflection for another male and attack it as part of territorial defense. This behavior happens most often in springtime, when birds are establishing their nesting territories and male testosterone levels are high. Covering the window with a screen, window film, or anything that prevents the bird from seeing its reflection is the best way to get birds to stop attacking the window. As the bird's hormones settle down, the defensive behavior typically stops on its own.
Alternatively, accidental window strikes happen when birds try to fly straight through a window because they can't see it. Learn about preventing window strikes here.
How do I protect bluebird nests from predators?
Bluebird boxes should be mounted on a self-supported pole with a baffle underneath that keeps climbing predators (e.g., raccoons, cats, snakes) from getting to the nest. If you check the nest, do so no more than once a day, and walk away in the opposite direction than how you approached. Curious nest predators can follow a dead-end scent trail right to the nest! Learn more about setting up a good bluebird box here.
Management
N.C. Wildlife Resources Commission biologists survey bluebirds, along with other songbirds, through the Breeding Bird Survey (BBS), which is the largest standardized survey method for breeding birds in the world. Routes have been surveyed across the continent for decades. Each 25-mile route is surveyed at least once each breeding season. A point count (location where all birds are identified by sight or sound) is taken every 0.5 miles. Data are analyzed over the decades to help determine bird population levels and changes over time.