Blue jays are bright blue on top and whitish gray on the belly and chin. They have a gray-blue, feather crested head, which they can raise and lower. The feathers on their wings and tails are bright blue with white and black bands. Blue jays also have a collar of black feathers across the throat and continuing around the head. Their bills, legs, feet, and eyes are black. Males are just a little larger, on average, than females. Total body length ranges from 22 to 30 cm. (Reilly 1968)
Blue jays are native to the Nearctic region. They are common in southern Canada and in the United States, east of the Rocky Mountains. (Sanford 1984)
Blue jays prefer mixed woodlands, particularly those with clearings. They are also common in suburban areas and city parks. (Reilly 1968)
Blue jays form long-lasting, monogamous pair bonds. These bonds usually last until one of the pair dies.
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. (Zims 1956, Reilly 1968)
Both males and females feed their nestlings. Young are able to feed themselves three weeks after they leave the nest, but stay with their parents for around two months after fledging.
The oldest blue jay studied by researchers in the wild lived to be 17 years and 6 months old, most blue jays live to about 7 years old. One captive female lived for 26 years and 3 months.
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. (Sanford 1984)
Blue jays use bobbing motions when courting and when fighting. A signal of submission may be the "body-fluff" when the bird crouches down and fluffs up its feathers, holding the crest erect.
Blue jays have many calls. The one that is probably most familiar is the "jay" call for which it is named. This probably attracts other jays to join a flock or serves as an alarm call. Another call sounds like a rusty pump handle, and another sounds like a bell. Blue jays also make rattling sounds. In the spring you can hear very soft singing.
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. (Reilly 1968)
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.
Because they hide seeds and nuts and sometimes forget to find and eat them, these birds probably help plants disperse their seeds.
There are no direct negative effects of blue jays on humans, although they may act as a reservoir for West Nile virus.
Blue jays are active and bold birds, making it easy to observe their fascinating behaviors.
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. (Reilly 1968)
Blue jays have been chosen as the mascot for many sports teams, including the Toronto Blue Jays, a professional baseball team.
Tanya Dewey (editor), Animal Diversity Web.
Jake Frysinger (author), University of Michigan-Ann Arbor.
Reilly, Edgar M. Jr. 1968. The Audubon Illustrated Handbook of American Birds. McGraw-Hill, New York. pp.307-308.
Sanford, William F. 1984. Academic American Encylopedia. Grolier Incorporated, Connecticut. p.343.
Zim, Herbert S. and Ira N. Gabrielson. 1956. Birds: A guide to the most familiar American birds. Golden Press, New York. pp.76, 142.