The Least Tern's name reflects its diminutive size. Despite the fact that it is the smallest of the terns, it commonly keeps company with larger terns at roosting and foraging sites. It may be seen assertively defending its nest by diving at intruders, calling shrilly while flying low over the water, or hovering above before plunging in to catch tiny prey.

Least Terns breed along both the Atlantic and Pacific coasts southward to Mexico, Central America, and the Caribbean. Inland populations breed along the Missouri, Ohio, and Mississippi Rivers, and other scattered inland locations. They winter along Mexican coasts south to South America.

Least Terns have the unfortunate distinction among North American terns of being classified for protection throughout much of their North American range. The Least Tern is a USFWS Bird of Conservation Concern, a continentally threatened species, and classified as "Threatened," "Endangered," or a "species of concern" in most states. Christmas Bird Count (CBC) and Breeding Bird Survey (BBS) data both indicate a decline for this species.  Although widespread and common in some places, many populations are endangered because the beaches needed for nesting are much in demand for human recreation and residential development. Inland, water fluctuation from dams often flood nesting sites along rivers.

Least Tern populations declined rapidly beginning in the late 1800s, due to feather hunting and egg collecting; they have been in flux ever since. Populations rebounded following passage of the 1916 Migratory Bird Treaty Act. However, since the 1940s, the nesting sites of many interior populations have been destroyed by flooding behind dams, channelization, and untimely water releases. Further population declines in the 1950s to 1970s were attributed to pesticide use and human disturbance of nesting habitats. Increased conservation efforts since the 1980s have helped restore some populations. However, recreational, industrial, and residential development in coastal breeding areas continues to diminish many populations.

 

Because of the endangered status of California and interior Least Terns, various agencies have monitored these populations in recent decades. But because Least Terns are relatively long-lived, reproductive problems are not immediately obvious. Thus, in addition to numbers, it is vital to monitor reproductive success. While Least Terns adapt to degraded habitat by readily shifting breeding sites, they seem most productive at sites with long-term stability. To encourage Least Terns to nest on protected habitat, they are sometimes lured to safer sites with decoys and recorded calls—techniques developed by Audubon's Seabird Restoration Program.

Never leave fishing lines, lures, or hooks on beaches; entanglement is usually lethal to terns.

 

Don't dump garbage or fishing bait which feeds competing gulls.

 

Don't disturb nesting tern colonies when hiking or landing boats; prevent dogs and children from disturbing them. When parent terns abandon their nests, eggs or chicks can overheat or become wet and chilled, often resulting in death.

 

Learn about seabird restoration projects for Least Terns and other seabirds at: http://www.projectpuffin.org

 

Thompson, B. C., J. A. Jackson, J. Burger, L. A. Hill, E. M. Kirsch, and J. L. Atwood. 1997. Least Tern (Sterna antillarum). In The Birds of North America, No. 290 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and the American Ornithologists Union, Washington, D.C.

 

Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, Inc., New York, 2000

 

Kaufman, Kenn. Lives of North American Birds. Houghton Mifflin Company, New York, 1996