Blue Jay, common name for a group of birds of the family that also includes the crows, ravens, and magpies. Most jays are smaller and more brightly colored than other members of the family; many of them have crests. Jays tend to be woodland birds, although several species have become urbanized and live in city parks. Most are noisy and are often found in flocks outside the breeding season. They are omnivorous, eating nuts (especially acorns), seeds, small amphibians, insects and other invertebrates, and sometimes the eggs and young of other birds.
There are few species of jays in Eurasia. The most widely distributed is the Eurasian jay, found all across the temperate and subtropical parts of Europe and Asia. The many subspecies vary in body color from gray to brown with a white rump and black tail. The crown varies from white, streaked black and white, to black. All have a bright blue-and-black barred patch on the wing coverts. Most are about 33 to 36 cm (about 13 to 14 in) long.
Most of the American jays are tropical, with species found from Mexico south to temperate South America. A few occur in North America, the best known of them the blue jay, found from the Great Plains to the Atlantic coast. It is about 30 cm (about 12 in) long, with a prominent crest. Its upperparts are grayish blue; the wings and tail are brighter blue, marked with black and white, and the underparts are light gray. Originally a woodland bird, it is now a familiar sight in many cities, nesting in shade trees. About the same size, but crestless, is the least colorful species, the gray jay, an inhabitant of northern and montane coniferous forests. It is mostly medium gray, with a white forehead, and is a fearless bird, often stealing food from hunters' camps.