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.