Adults: Black cap, nape, and eye stripe; white forehead, lower face, and underparts; gray wings amd tail; outer primaries (flight feathers) darker gray; bill, legs, and feet yellow. Juveniles: Mottled browns and grays above. 23 cm (9 in) in length; 51 cm (20 in) wingspan. The Least Tern is the smallest tern in North America and has a long forked tail.
The breeding season begins in May. Breeding habitat includes areas of sandy or gravel beaches along the coast, rivers, or lakes. The Least Tern nests in colonies. The nest scrape is built by the female in the sand or gravel and sometimes is lined with fine plant material. The female lays 1-3 (usually 2) eggs that she and the male incubate for 20-22 days. The young are semi-precocial and remain in the nesting area for 19-20 days. They are cared for by both adults during that time.
The habitat used by the Least Tern during the non-breeding sesaon is similar to its breeding season habitat. Its diet consists of fish, aquatic invertebrates, and crustaceans. The Least Tern finds its food by searching while in flight and diving into the water to catch the prey. This species is migratory.
During the breeding season, the Least Tern occurs throughout most of the coastal United States and inland along some of the larger river systems. This species winters from Mexico to northern South America.
This species is federally listed as Endangered. In the Southeast, the Least Tern is state-listed as Endangered in Kentucky, Tennessee, Louisiana, and Arkansas. Its decline began with hunting of this bird for its plumes for the fashion industry in the late 1800s and early 1900s, until the Migratory Bird Treaty Act of 1918 was enacted to protect all native bird species. Many urban pests, like cats, rats, and humans, disturb nesting birds and may cause the Least Tern to desert its nest.
The most similar species are the other terns with long forked tails, including the Roseate Tern and Forester's Tern. Both of these species are larger than the Least Tern, have a black forehead instead of the Least Tern's white one, and have red-orange feet and legs.