Eurasian jay plumage is mainly light reddish brown. Their feathers reflect UV light. Their crests, which are frequently raised during communication, are white with black speckles. Their beaks are black, and black moustache stripes extend downward from the ends of their beaks. Their tails are black dorsally with a white patch around the base. Their wings have bright blue spots with black speckles. These blue areas appear like triangles or a band, though their orientation and size changes when the wings are spread (they enlarge when spread). There are white bands on the wings, visible during flight. The rest of the wings are black, except for a red triangle where the wing attaches to the body. They often carry their wings so the tips are both on one side of the tail.
When compared to other corvids, like Corvus and Pica species, Eurasian jays hold their tail rather high. For this reason the tail feathers incur less damage than in the other genera. Unlike other corvids, Eurasian jays have two plumage phases: juvenile and adult. Other corvids can be aged by a sequence of plumages, but ageing is more difficult in Eurasian jays. They lose their juvenile plumage by autumn of the first year, so birds seen in autumn all appear to be adults.
Eurasian jay average basal metabolic rate is 4.99 kJ per hour.
Average mass: 170 g.
Average length: 34 cm.
Average wingspan: 55 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger