Birds
Jay
Garrulus and relatives · also called jays
A jay is a crow that dresses up and hides in the trees. Where a crow is black and out in the open, a jay is patterned with blue, pink, or bright markings and keeps to the woodland canopy, screeching when disturbed and vanishing. Its real work is done in autumn, when a single bird buries thousands of acorns across the countryside and forgets enough of them to seed the next generation of oaks.
Overview
Jays are not one species but a scattering of crow-family birds — the pinkish Eurasian jay, the blue jay of eastern North America, the grey Canada jay, and the many scrub and pinyon jays of the American West. They are omnivores built around a seasonal cycle: acorns, nuts, and pine seeds in the cold months, insects and the odd egg or nestling in spring.
The acorn planter
A Eurasian jay may bury 4,000 to 5,000 acorns in a single autumn, carrying a beakful and a gullet-full at a time and pushing each one into the ground. Because it never retrieves them all, the jay is one of the main natural planters of oak woodland, and one of the few animals that moves acorns uphill and into the open. It has an excellent memory for its own caches — and will re-hide food if another bird is watching, a sign it can reason about what a rival knows.
Voice and habits
Many jays are good mimics, especially of birds of prey, and the Eurasian jay’s tearing screech is a classic woodland alarm. Jays are also frequent “anters”, letting ants swarm through their feathers to fight parasites. A blue jay’s blue, incidentally, is structural colour — crush the feather and it turns brown.
Status
Least Concern — most jays are common and several have expanded into gardens and suburbs. The exceptions are habitat specialists: the Florida scrub-jay (Threatened) and the tiny-range island scrub-jay of California.
Jay: common questions
What is the difference between a jay and other crows?
Jays are members of the crow family, Corvidae, but the name jay is used for the smaller, often more colourful, more woodland species rather than for a single natural group. Compared with a typical crow, a jay is usually smaller, more boldly patterned, often blue, pink, or brightly marked rather than plain black, tends to stay among trees rather than out in open fields, and relies heavily on stored nuts and seeds. Crows and ravens are larger, mostly black, more terrestrial, and more likely to scavenge. In intelligence and social behaviour, though, jays are true corvids, with the same problem-solving ability, long memory, and complex family life.
Do jays really plant oak trees?
Yes, to a remarkable degree. Oaks produce heavy acorns that fall straight down and cannot spread on their own, so oak woodland depends on animals to carry acorns away, and the jay is the most important of those animals in Europe and a major one in North America. Each jay hides thousands of acorns every autumn, singly, pushed into the ground in just the conditions a seedling needs, often hundreds of metres from the parent tree and in open ground or on hillsides where oaks are colonising. The acorns the jay fails to recover germinate, and studies of how oak forests regrew after the last ice age point to jays as the key long-distance seed carriers.
Why do jays scream?
The loud, harsh, tearing screech is mainly an alarm and mobbing call. A jay that spots a cat, fox, bird of prey, or person will screech repeatedly, alerting its mate and other birds and often drawing a crowd of small birds to harass the predator. Jays also use the call to advertise a territory and to keep in contact through dense cover where they cannot see one another. Because jays are shy woodland birds, the screech is frequently the only sign that one is present, which has made the jay a byword for a noisy sentinel of the woods.
Are jays aggressive toward other birds?
Jays do take eggs and nestlings in spring, and at feeders a jay will often dominate smaller birds, so they have a reputation as bullies and nest robbers. The reality is more moderate. Nest predation by jays is real but is a normal part of woodland life and is not a significant cause of songbird decline, which is driven far more by habitat loss. At feeders jays tend to be wary, grabbing food and carrying it off rather than holding the feeder for long. For most of the year a jay is a secretive bird far more interested in acorns than in other birds.