Size: L: 20 cm. Wt: 50 g. Males and females are sexually dimorphic in colour. Males take two years to reach adult plumage.
Adult Male: body completely glossy purplish-blue, with long, pointed wings and a deeply notched tail; bill small, black; legs black
1st Spring Male: upperparts dull purplish-blue, with glossy areas on head, wings, and tail; forehead purplish-blue; neck greyish in front, purplish-blue on nape; underparts greyish, with some flecks of purple; bill and legs as in adult male
Female: upperparts dull purplish-blue, with glossy areas on head, wings, and tail; forehead and neck sooty grey; underparts grayish; bill and legs as in male
Juvenile: upperparts grey-brown, chin and throat grey-brown; underparts greyish-white; bill and legs as in adult