Least tern Sterna antillarum

Identification Tips:

• Sexes similar
• Flies with very rapid wingbeats
• Dives into water for prey
• Diminutive tern with slender, pointed bill
• Very short legs
• Short, forked tail
• Smoothly rounded head without crest
• Pale underwing with blurry primaries along leading edge

Adult alternate:

• Yellow legs
• Yellow bill with tiny black tip
• Black cap with white forehead patch before eye
• White face, foreneck, breast, and belly
• Pale gray rump and tail
• Entirely gray back and upperwing with dark outer two primaries

Adult basic:

• Orange legs
• Black bill
• White forehead, face, foreneck, breast, and belly
• Black cap mottled with white
• Entirely gray back and upperwing with dark outer two primaries

Juvenile:

• Pale orange legs
• Pinkish bill becomes black with age
• White forehead, foreneck, breast, and belly
• Black eye patch
• Pale crown streaked with brown and black
• Pale brown back with brownish center to feathers
• Dark carpal bar
• Gray wings with brown tips to upperwing coverts
• Dark outer five primaries forms bold, dark, wedge in flight
• Short tail with dark gray-brown tips

First winter/First summer:

• Black bill and legs
• Black half hood
• Pale forehead
• Pale crown streaked with black
• Dark carpal bar

Similar species:

No other North American tern approaches the Least Tern in size except the Black Tern. When flying the wingbeats often are so rapid that they cannot be counted. Most larger terns fly with wingbeats slow enough to be counted. Black Tern is closest in size but has a swallow-like flight, rarely dives for prey, is dark gray above and has a dark gray tail and is entirely black below in adult alternate plumage. The yellow bill and legs, and white forehead of the adult Least Tern are distinctive at rest.