Interior Least Terns
(Sternula antillarum athalassos)

The Interior Least Tern is a state and federally protected endangered species. It is the smallest tern in North America. The Interior Least Tern is an energetic, swallow-like bird with a deeply forked tail and slender wings. They are graceful, agile flyers and are often observed hovering over bodies of water and diving to catch small fish.

Interior Least Terns are:

  • slightly smaller than a robin
  • 9 inches long from beak to tail
  • 20 inches from wing tip to wing tip

Appearance

Breeding Adult
white body
black cap with white forehead
light gray wings
yellow bill with black tip
yellow-orange legs

 

Winter Adult
paler than breeding birds
dark grey eye strip
white forehead with dusky brown cap
brownish-black bill
pale yellow legs
Breeding adult Interior Least Tern
Breeding adult Interior Least Tern
Juvenile (1 years old)
closely resembles winter adult
mottled gray-white body
white forehead with dusky brown cap
dark bill
orange-black legs
Juvenile Interior Least Tern
Juvenile Interior Least Tern

Vocalization

Sound byte Courtesy of The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, New York. Recordist: Charles A. Sutherland.