Blue Jay Life History

Habitat

Habitat ForestsBlue Jays are found in all kinds of forests but especially near oak trees; they’re more abundant near forest edges than in deep forest. They’re common in urban and suburban areas, especially where oaks or bird feeders are found.Back to top

Food

Food OmnivoreBlue Jays glean insects and take nuts and seeds in trees, shrubs, and on the ground; they also eat grains. They also take dead and injured small vertebrates. Blue Jays sometimes raid nests for eggs and nestlings, and sometimes pick up dead or dying adult birds. Stomach contents over the year are about 22 percent insect. Acorns, nuts, fruits, and grains made up almost the entire remainder. Of 530 stomachs examined, traces of bird eggs and nestlings were found in only 6 stomachs, although a search was specially made for every possible trace of bird remains. Blue Jays hold food items in feet while pecking them open. They store food in caches to eat later. Back to top

Nesting

Nest Placement

Nest TreeBlue Jays build their nests in the crotch or thick outer branches of a deciduous or coniferous tree, usually 10-25 feet above the ground. Male and female both gather materials and build the nest, but on average male does more gathering and female more building. Twigs used in outer part of nest are usually taken from live trees, and birds often struggle to break them off. Birds may fly great distances to obtain rootlets from recently dug ditches, fresh graves in cemeteries, and newly fallen trees. Jays may abandon their nest after detecting a nearby predator.

Nest Description

Open cup of twigs, grass, and sometimes mud, lined with rootlets.

Nesting Facts
Clutch Size:2-7 eggs
Number of Broods:1 brood
Egg Length:1.0-1.3 in (2.5-3.3 cm)
Egg Width:0.7-0.9 in (1.8-2.2 cm)
Incubation Period:17-18 days
Nestling Period:17-21 days
Egg Description:Bluish or light brown with brownish spots.
Condition at Hatching:Naked and helpless, eyes closed, mouth lining red.
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Behavior

Behavior Ground ForagerThis common, large songbird is familiar to many people, with its perky crest; blue, white, gray, and black plumage; and noisy calls. Blue Jays are known for their intelligence and complex social systems, and have tight family bonds. They often mate for life, remaining with their social mate throughout the year. Only the female incubates; her mate provides all her food during incubation. For the first 8–12 days after the nestlings hatch, the female broods them and the male provides food for his mate and the nestlings. Female shares food gathering after this time, but male continues to provide more food than female. Some individual nestlings begin to wander as far as 15 feet from the nest 1-3 days before the brood fledges. Even when these birds beg loudly, parents may not feed them until they return to the nest; this is the stage at which many people find an “abandoned baby jay.” If it can be restored to or near the nest, the parents will resume feeding it. The brood usually leaves the nest together usually when they are 17-21 days old. When young jays leave the nest before then, it may be because of disturbance. The jays are usually farther than 75 feet from the nest by the end of the second day out of the nest. Young remain with and are fed by their parents for at least a month, and sometimes two months. There is apparently a lot of individual variation in how quickly young become independent. Blue Jays communicate with one another both vocally and with “body language,” using their crest. When incubating, feeding nestlings, or associating with mate, family, or flock mates, the crest is held down; the lower the crest, the lower the bird’s aggression level. The higher the crest, the higher the bird’s aggression level; when a Blue Jay squawks, the crest is virtually always held up. Blue Jays have a wide variety of vocalizations, with an immense “vocabulary.” Blue Jays are also excellent mimics. Captive Blue Jays sometimes learn to imitate human speech and meowing cats. In the wild, they often mimic Red-shouldered and Red-tailed hawks, and sometimes other species. Blue Jays are disliked by many people for their aggressive ways, but they are far less aggressive than many other species. In one Florida study, Red-bellied Woodpeckers, Red-headed Woodpeckers, Florida Scrub-Jays, Common Grackles, and gray squirrels strongly dominates Blue Jays at feeders, often preventing them from obtaining food, and Northern Bobwhites, Mourning Doves, White-winged Doves, Northern Mockingbirds, and Northern Cardinals occasionally dominated them as well. Sometimes Blue Jays mimic hawks when approaching feeders. This may deceive other birds into scattering, allowing the Blue Jay to take over the feeder, but most birds quickly return after the jay starts feeding. Blue Jays carry food in their throat and upper esophagus—an area often called a “gular pouch.” They may store 2-3 acorns in the pouch, another one in their mouth, and one more in the tip of the bill. In this way they can carry off 5 acorns at a time to store for later feeding. Six birds with radio transmitters each cached 3,000-5,000 acorns one autumn. Their fondness for acorns and their accuracy in selecting and burying acorns that have not been infested with weevils are credited with spreading oak trees after the last glacial period. Despite being common, conspicuous birds that have been studied by many researchers, much about Blue Jays remains a mystery. This is the only New World jay that migrates north and south, and large flocks are observed flying over many hawkwatch spots, along shorelines, and at other migration overlooks, but their migration is very poorly understood. Some individuals remain year-round throughout their entire range, and at least some individuals depart during spring throughout their entire range except peninsular Florida. Migrating flocks can include adults and young birds, and recent analyses of movements of banded jays indicate that there is no age difference between jays that migrate and jays that remain resident. The proportion of jays that migrate is probably less than 20 percent.Back to top

Conservation

Conservation Low Concern

Blue Jay populations decreased by about 28% between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 13 million, with 87% living in the U.S. and 13% living in Canada. The species rates an 8 out of 20 on the Continental Concern Score and is not on the 2016 State of North America's Birds' Watch List. The most frequent cause of death associated with humans comes from attacks by cats and dogs.

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Backyard Tips

Blue Jays prefer tray feeders or hopper feeders on a post rather than hanging feeders, and they prefer peanuts, sunflower seeds, and suet. Planting oak trees will make acorns available for jays of the future. Blue Jays often take drinks from birdbaths. Find out more about what this bird likes to eat and what feeder is best by using the Project FeederWatch Common Feeder Birds bird list.

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Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

Smith, Kimberly G., Keith A. Tarvin and Glen E. Woolfenden. 2013. Blue Jay (Cyanocitta cristata), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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