Blue Jay (Cyanocitta cristata): Facts, Calls and Behavior

Appearance: how to recognize a blue jay

A blue jay is easy to know at a glance. The crest, back, wings and tail are lavender-blue to bright blue, while the face, throat and underparts are white to pale gray. A black “necklace” runs around the throat and up the sides of the head, and the wings and tail are crossed with black bars and spotted with white.

The crest is a mood indicator. A jay raises it high when it is excited, alarmed or aggressive, bristles it outward when frightened, and lays it flat when it is relaxed or feeding quietly with other jays.

Males and females look the same, although males are slightly larger. The black markings on the face vary from bird to bird, and researchers think jays may use these differences to recognize one another. Young jays look like duller, grayer versions of their parents.

Strangely, the blue jay is not truly blue. Its feathers contain no blue pigment; the color comes from tiny structures that scatter blue light, as explained in are blue jays really blue?.

Size: how big is a blue jay?

The blue jay is a medium-sized songbird, larger than an American robin but much smaller than an American crow.

Body size follows a pattern called Bergmann’s rule: jays in the colder north tend to be heavier than those in the warm south. Birds measured in Connecticut averaged about 92 g (3.3 oz), while those in southern Florida averaged about 74 g (2.6 oz).

Habitat and range

Blue jays live from southern Canada through the eastern and central United States, south to Florida and northeastern Texas. To the west, their range stops roughly where the dry pine and scrub country of the Steller’s jay begins, along the eastern foothills of the Rocky Mountains. Where the two species now overlap, they occasionally hybridize.

Their favorite habitat is mixed woodland with oaks and beeches, but they are flexible. They live in pine woods in Florida, spruce and fir forests in Ontario, farmland with woodlots, city parks, cemeteries and leafy suburbs. They are less common deep inside dense, unbroken forest than along edges.

Over the last century, the planting of trees and the suppression of wildfires across the Great Plains have let blue jays spread westward. Today a few reach the Pacific coast in winter as rare but regular visitors.

Diet: what do blue jays eat?

Blue jays are omnivores, but plants make up most of what they eat. Classic studies of stomach contents found that about 75 percent of their food is vegetable matter: acorns, beechnuts, hazelnuts, weed seeds, grain, berries and other fruit. At bird feeders they favor peanuts, sunflower seeds and suet.

The rest is animal food. They eat caterpillars, beetles, grasshoppers and other insects, spiders and snails, and sometimes frogs, mice or the eggs and nestlings of other birds. Jays hold a nut with their feet and hammer it open with their strong black bill.

Each fall, blue jays harvest and bury huge numbers of acorns and other nuts to eat in winter. They carry several at a time in a pouch in the throat. A single jay may cache thousands of acorns in one season, and the ones it never recovers can grow into new trees; the full story is in do blue jays plant oak trees?.

Calls, mimicry and communication

The blue jay is one of the noisiest birds in North America. Its best-known sound is a loud, harsh “jay! jay!” scream, often used as an alarm. Other birds and squirrels recognize it, and a jay’s alarm can send a whole backyard into hiding.

Jays also have quieter calls that are easy to overlook: a musical, two-note “bell” or “pumphandle” call, a squeaky “rusty pump” sound, clicks, rattles and a soft, rambling whisper song given when a bird is alone or close to its mate.

Blue jays are skilled mimics. They often copy the screams of red-shouldered and red-tailed hawks so well that even experienced birders can be fooled. Why they do it is still debated; the main ideas are covered in do blue jays mimic hawks?. Captive blue jays have also learned to copy human speech and household sounds.

Behavior and intelligence

Like other members of the crow family, such as the American crow, blue jays are curious and clever. Young jays pick up shiny objects such as bottle caps and foil and carry them around until they lose interest. Captive jays have used strips of newspaper as tools to rake in food, and a wild jay has been seen using a piece of bark to help catch a spider.

Blue jays are known for mobbing: when they find a hawk, owl, cat or snake, they gather, call loudly and swoop at it until it moves away. This protects their own nests but also warns other birds. If an owl roosts near a jay’s nest in daytime, the jays may harass it until it leaves.

Their reputation as bullies is only partly deserved. Jays do chase smaller birds from feeders, but they are often pushed around themselves. In Florida studies, gray squirrels, Florida scrub-jays, common grackles and red-headed woodpeckers regularly drove blue jays away from feeders.

Do blue jays migrate?

Blue jays are partial migrants, and their migration is one of the small mysteries of North American birding. In fall, loose flocks of 5 to 250 jays travel by day along the Great Lakes shores and the Atlantic coast, and observers at well-known lookouts can count thousands in a season. Yet many jays stay in the north all winter.

Banding studies show that some individuals migrate one year, stay put the next and migrate again later. Young birds seem more likely to travel than adults. The best explanation so far is that jays respond to weather and to the size of the local acorn and nut crop, but no one has yet worked out the full answer.

Reproduction and life cycle

Blue jays are believed to form long-lasting, monogamous pairs. Courtship begins in late winter, and nesting runs from about mid-March into July, peaking in April and May.

Both partners build an open cup nest of twigs, rootlets, bark strips and moss, sometimes cemented with mud and lined with fine roots. They usually place it 3–10 m (10–33 ft) up in the fork of a tree, often an evergreen. Close to the nest, the normally loud jays become silent and secretive.

• Eggs: usually 3–6 (most often 4 or 5), bluish or light brown with brown spots.
• Incubation: about 16–18 days, by the female, while the male brings her food.
• Fledging: the chicks leave the nest about 17–21 days after hatching.

After fledging, the young stay with their parents for one to two months, traveling and feeding together as a family. They disperse in early fall and can breed when they are about one year old.

Lifespan

Wild blue jays that survive their first year usually live about 7 years. Banding records show that some live much longer: one wild jay reached about 17 and a half years, and another banded in Newfoundland and Labrador was at least 26 years old when it was found in 2016.

The eggs and nestlings face many predators, including tree squirrels, snakes, crows, raccoons, opossums and cats. Adults are caught mainly by bird-hunting hawks such as Cooper’s hawks and sharp-shinned hawks, and by owls. Because jays fly at an unhurried 32–40 km/h (20–25 mph), they are vulnerable when crossing open ground. West Nile virus, which hits the crow family hard, has caused local declines, but not a lasting drop across the range.

Conservation status

The blue jay is listed as Least Concern on the IUCN Red List. It is common and widespread, with an estimated breeding population of roughly 13 million birds according to Partners in Flight. Long-term North American Breeding Bird Survey data show declines along the Atlantic coast but increases in the northern part of the range, such as Labrador, Nova Scotia, southern Quebec and southern Manitoba.

Blue jays adapt well to people, as long as there are trees for nesting and nuts or seeds to eat. In the United States they are protected under the Migratory Bird Treaty Act, and in Canada under the Migratory Birds Convention Act.

Myths and facts

Myth: blue jays mostly live by stealing eggs. Jays do sometimes raid nests, but the evidence shows it is a small part of their diet. In large stomach-content studies, bird eggs or nestlings appeared in only a few percent of jays, and plant food made up most of their meals.

Myth: a blue jay feather is blue. The color is produced by the structure of the feather, not by pigment. A feather lit from behind or crushed looks dull gray-brown.

Fact: jays help plant forests. By burying acorns and beechnuts far from the parent tree, often in open ground that suits seedlings, blue jays are some of the most important seed dispersers for oaks in eastern North America.

Blue jays and people

The blue jay is the provincial bird of Prince Edward Island and gave its name and logo to the Toronto Blue Jays baseball team. It is the mascot of several universities, including Johns Hopkins and Creighton. In old African American folktales from the southern United States, the blue jay was a powerful figure, credited in some stories with bringing the first grains of dirt to make the earth.

For many people in eastern North America, the jay’s harsh scream and flash of blue are among the most familiar sights and sounds of a backyard in fall and winter.