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blue jay

Cyanocitta cristata

What do they look like?

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)

  • Sexual Dimorphism
  • male larger
  • Range mass
    65 to 109 g
    2.29 to 3.84 oz
  • Range length
    22 to 30 cm
    8.66 to 11.81 in

Where do they live?

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)

What kind of habitat do they need?

Blue jays prefer mixed woodlands, particularly those with clearings. They are also common in suburban areas and city parks. (Reilly 1968)

How do they reproduce?

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)

  • How often does reproduction occur?
    In the north, only one brood per year may be produced. In southern regions, however, Blue Jays may raise two broods each year.
  • Breeding season
    Blue Jays breed from March through July.
  • Range eggs per season
    3 to 6
  • Average eggs per season
  • Average time to hatching
    17 days
  • Average time to hatching
    17 days
  • Range fledging age
    17 to 21 days
  • Average time to independence
    3 months
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

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.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

How long do they live?

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.

  • Range lifespan
    Status: wild
    17.5 (high) years
  • Range lifespan
    Status: captivity
    26.25 (high) years
  • Average lifespan
    Status: wild
    7 years
  • Average lifespan
    Status: wild
    210 months
    Bird Banding Laboratory

How do they behave?

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)

How do they communicate with each other?

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.

What do they eat?

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)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • eggs
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

What eats them and how do they avoid being eaten?

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.

What roles do they have in the ecosystem?

Because they hide seeds and nuts and sometimes forget to find and eat them, these birds probably help plants disperse their seeds.

  • Ecosystem Impact
  • disperses seeds

Do they cause problems?

There are no direct negative effects of blue jays on humans, although they may act as a reservoir for West Nile virus.

How do they interact with us?

Blue jays are active and bold birds, making it easy to observe their fascinating behaviors.

Are they endangered?

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)

Some more information...

Blue jays have been chosen as the mascot for many sports teams, including the Toronto Blue Jays, a professional baseball team.

(Reilly 1968)


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.

University of Michigan Museum of ZoologyNational Science Foundation

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Frysinger, J. 2001. "Cyanocitta cristata" (On-line), Animal Diversity Web. Accessed May 30, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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