Wednesday, October 19, 2011

Blue Jays -- © Dave Spier

How would you describe Blue Jays (Cyanocitta cristata)? Noisy? Large? Bullies? Beautiful? Depends what you're doing (or what they're doing), I suppose. If you're a hunter or wildlife photographer, jays announce your presence to the rest of the forest world. If you feed birds, do the jays unintentionally (or intentionally) scare smaller birds away? Or worse, does a blue jay ever attack or even eat a smaller bird?
Jays are corvids (members of the Corvid, or crow, family) and share many characteristics with cousin crow. They have sturdy, all-purpose bills and they eat whatever they can find, or sometimes catch. They're right at home at bird feeders eating sunflower seeds and suet, but their natural diet includes a lot of nuts. They depended on chestnuts before that tree species was wiped out by blight. Then they shifted entirely to acorns and beechnuts. Many of these are "stored" underground for winter retrieval, much the way squirrels hide food, and the forgotten nuts grow into new oaks and beech trees. A single jay can stash up to 5000 acorns in a season, an average of 110 per day. The acorns are carried in the beak, the equivalent of us carrying a coconut in our mouth. Smaller acorns are carried four or five at a time using the throat and mouth as well as the bill. Jays are credited with reintroducing chestnuts, oaks and beech to New York and northward after the retreat of the glacier at the end of the last Ice Age. At the other extreme, oaks are absent from the world wherever there are no species of jays.
Jays have been known to eat parts of roadkills, but this niche is filled more by their larger black relatives, the crows and ravens. In the spring, Blue Jays have a bad reputation for eating the eggs and nestlings of smaller bird species, another habit shared with crows. During the warmer months, they eat salamanders, tree frogs, small snakes, snails, spiders, many beetles, grasshoppers, caterpillars and other insects. In late summer and fall they eat berries, corn and small rodents. On an annual basis, their diet is 76% vegetarian, 23% insects and only one percent vertebrates.
Blue Jays are year-round residents even though they seem to disappear into the trees during breeding season. They become silent to avoid drawing attention to their nests and avoid the spotlight on themselves as they prey on other nests. They raise one brood a year in the North, but the clutches are larger than those of jays in the South which have time for two or three broods.
Fledgling Blue Jays are scruffy copies of their parents. Males and females have identical plumage and may tell each other apart by voice or behavior. Females tend to be smaller. Their predominantly blue color is an optical illusion. Unlike paint pigments, the blue is created by microscopic flakes of melanin on the feathers that reinforce the blue spectrum and interfere with other colors. The bright blue wings and long tail are decorated with black bars and patches of white feather tips. The back and crest are a uniform darker blue. A dark necklace encircles a dirty white face and throat. The breast is light gray and the belly is nearly white.
After nesting season, jays resume their role as town criers. In fall they gather into small flocks and some (more likely the youngsters) migrate south. The remaining birds concentrate around dependable feeders where they are usually the largest visitors. Only Mourning Doves and grackles are larger. The Red-bellied Woodpecker, being slightly shorter, comes close in size and Hairy Woodpeckers are close behind red-bellies.
Shrikes are listed in the field guides as shorter than Blue Jays, but apparently they're strong enough to tackle the jay. I received a report of a shrike attacking a Blue Jay in the woods and carrying the struggling prey 50 feet. The shrike then nailed the jay to the ground and they struggled again. The shrike took off with the Blue Jay still in its beak and flew another 50 feet before the jay managed to get away. Shrikes lack the strong talons of a hawk and are incapable of killing their prey on the first strike. Had the predator been an Accipiter, or bird hawk, the jay would have become an instant meal. A Cooper’s Hawk would have little trouble dispatching a jay.
European visitors are envious that the spectacular Blue Jay is a common yardbird here. Perhaps we should admire its beauty and overlook what some people consider its faults, its aggressive behavior exhibited primarily during nesting season.

For a discussion of Adirondack Blue Jays, see the Adirondack Naturalist blog.
Questions and corrections may be sent to

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