Female Blue Jays Choose a Mate
Any time from late winter through early spring, female blue jays will pick a male to mate with. It is believed that older birds go through the process earlier than younger blue jays. When ready to pick a mate, female blue jays gather a crowd of half a dozen or more potential mates in a tree. From there, she takes flight and the males follow her, making lots of noise. The males land when the female lands, and fly again when she does. Each time the flock lands, the males bob their heads up and down energetically. Some will tire and assume a submissive position, crouching and ruffling their feathers. They will stay behind as the more persistent blue jays continue to follow the female around. By the end of the day, one male will remain, and he will pair with the female. Blue jays pair until one of them dies.
Building the Nest
After blue jays pair, the male will feed the female as a manner of bonding. They will then build several partially-completed practice nests together. The male finds the best twigs for their purpose that he can, which the female will inspect and choose from. After a few incomplete nests, the blue jay pair will settle on a location for the final product, in the fork of tree branches, generally anywhere from 10 to 30 feet above ground. The final nest will be built mostly by the female, out of twigs, bark, moss, foliage, some suitable man-made materials, and mud, which is used as mortar. The process of building the practice nests and the final one typically goes on for a few weeks.
Blue Jay Reproduction
As male birds have no external penis, the male mounts the female from behind and rubs his cloaca against the female's, passing sperm into her. In a few weeks, the female blue jay will lay three to five eggs.
Blue jay eggs are incubated for a little over two weeks. The female sits on the eggs almost the entire time, being fed and protected by the male. Blue jays are infamously fierce defenders of their nests, eggs, and chicks. Once the newborns hatch, they will remain in the nest for two months, and they will stay with their family for some time after that. The male shares in the responsibilities of feeding, caring for, and protecting the offspring.