Blue jays are natural forest dwellers, but they are also highly adaptable and intelligent birds. They are a familiar and noisy presence around many North American bird feeders. The blue jay's "Jay! Jay!" call is only one of a wide variety of sounds the bird employs-including excellent imitations of several hawk calls. Blue jays are sometimes known to eat eggs or nestlings, and it is this practice that has tarnished their reputation. In fact, they are largely vegetarian birds. Most of their diet is composed of acorns, nuts, and seeds-though they also eat small creatures such as caterpillars, grasshoppers, and beetles. Blue jays sometimes store acorns in the ground and may fail to retrieve them, thus aiding the spread of forests. Common in much of eastern and central North America, blue jays are gradually extending their range to the Northwest. They are fairly social and are typically found in pairs or in family groups or small flocks. Most northern birds head south for the winter and join in large flocks of up to 250 birds to make the long journey. However, this migration is a bit of a mystery to scientists. Some birds winter in all parts of the blue jay's range, and some individual birds may migrate one year and not the next. It is unclear what factors determine whether each blue jay or family decides to migrate.
Blue Jay Habitat
Blue jays prefer mixed woodlands, particularly those with clearings. They are also common in suburban areas and city parks. Blue jays are native to the Nearctic region. They are common in southern Canada and in the United States, east of the Rocky Mountains. Blue jays build loose and untidy nests of barks, twigs, leaves, and grasses in trees and shrubs. The female lays three to six eggs at a time. These can be blue, green, or yellow, with brown or grey spots. The eggs must be incubated for 17 to 18 days. This is usually done by female, but in some cases males share in the incubation. Males provide food for females during incubation. Young fledge after 17 to 21 days and leave their natal range about 2 months after fledging. Blue jays may breed in their first year after hatching. Blue jays are very aggressive and noisy birds,driving other birds away from food sources and their territories. In the winter, Blue jays hide far more food than they can eat, perhaps to remove food from their territories to discourage intruders. They are also partially migratory, and in the fall they can be seen traveling in flocks of more than a hundred birds. Blue jays are omnivorous. They feed on fruits, nuts, seeds, insects, mice, frogs, and will rob other nests for small songbirds and bird eggs. To eat nuts, blue jays hold them with their feet and then crack the shell with their bill. Blue jays in captivity have been known to fashion tools in order to get at foods. Blue jays will also steal foods from other birds by frightening them into dropping what they have. They cache foods, such as seeds, for later use. Blue jays will actively defend their nests against predators. Both parents will attack and chase hawks, falcons, raccoons, cats, snakes, squirrels, and even humans away from their nests. Adult blue jays are often preyed on by various species of hawks, owls, and falcons. Nestlings are preyed upon by squirrels, cats, snakes, American crows, other jays, raccoons, opossums, and birds of prey, such as hawks. Blue jays will actively defend their nests against predators. Both parents will attack and chase hawks, falcons, raccoons, cats, snakes, squirrels, and even humans away from their nests. Adult blue jays are often preyed on by various species of hawks, owls, and falcons. Nestlings are preyed upon by squirrels, cats, snakes, American crows, other jays, raccoons, opossums, and birds of prey, such as hawks. Blue jay populations are on the rise, and they are often very common where they occur. The range is expanding westward. Populations may have suffered somewhat in previous centuries as their wooded habitats were cleared and may suffer where epidemics of West Nile virus affect bird populations. Blue jays are corvids, which seem particularly susceptible to this virus. Blue jays have been chosen as the mascot for many sports teams, including the Toronto Blue Jays, a professional baseball team.
[source: National Geographic]