Feeding in both trees and on the ground, it takes a wide range of invertebrates including many pest insects, acorns (which it buries for use in hard times during winter), beech mast and other seeds, fruits such as blackberries, rowan berries etc., young birds, mice, small reptiles and small snakes.
It nests in trees or large shrubs laying usually 4-6 eggs that hatch after 16-19 days and are fledged generally after 21-23 days. Both sexes typically feed the young.
The species is well known for its mimicry, often sounding so like another bird singing that it is virtually impossible to distinguish its true identity unless the jay is seen. It will even imitate the sound of the bird it is attacking, such as a Tawny Owl, which it does mercilessly if found through the day. The tables are turned though as the jay is a potential prey item for owls at night. The usual call heard, however, is the alarm call which is a harsh, rasping screech and is used upon sighting various predatory animals.