Size: L: 35 cm Wt: 120 g. Males and females are similar. Seasonally dimorphic. This species requires three years to reach full adult plumage.
Summer Adult: mantle and wings grey, with some blackish on outer primaries; head white, with black forehead, crown, and nape; underparts pale grey; tail forked, white; bill sharply pointed, red with small black tip; legs red
Second Summer: similar to summer adult, but with no blackish on outer primaries; bill with more black on tip
First summer: mantle and wings grey, with dark gray carpal bar and wing-tips; head with white forehead, and dusky crown and nape; underparts whitish; tail forked, greyish, may have dark markings on outer rectrices; bill black; legs red
Juvenile: similar to first summer, but mantle mottled light grey-brown; wings with blackish primary tips; bill pinkish, with black tip
Nestling: semiprecocial and downy; down long, soft; upperparts buffy or gray, patterned with blackish-brown; mantle and back with a pair of dark, median streaks; chin white; lores and throat dusky; underparts whitish; bill orange, with blackish tip; legs and feet pink to yellowish-orange