Size: L: 15 cm. Wt: 20 g. Males and female are sexually dimorphic in colour. Females take two to three years to reach adult plumage.

Male: upperparts glossy blue-green, with long, pointed wings and notched tail; underparts pure white; bill small, black; legs pale brown

Subadult Female: upperparts dusky grey-brown, may have flecks of blue-green throughout; underparts pure white; bill and legs as in adult male

Adult Female: upperparts blue-green, usually less pure and glossy than in male; forehead often brownish; underparts pure white; bill and legs as in adult male

Juvenile: upperparts dull gray-brown, with no blue-green flecks; underparts white, may have pale gray wash on breast; bill and legs as in adult male

Nestling: altricial and downy; skin pale pink; down whitish; mouth pale yellow; gape flanges white