Least Tern

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Image:Leasttern.jpg

Common Name: Least Tern
Scientific Name: Sternula antillarum (formerly Sterna antillarum)

Size: 8.5-9 inches (22-24 cm)

Habitat: North and South America; breeds in North America and locally in northern South America.

Status: Least Concern/Endangered. Global Population: 65,000 - 70,000 mature individuals. Although widespread and common in places, its favored nesting habitat is prized for human recreation, residential development, and alteration by water diversion, which interfere with successful nesting in many areas. It is classified as "Threatened," "Endangered," or "species of concern" for most states because of loss of nesting habitat. Interior Population federally listed as "Endangered" in 1985.

Diet: Anchovy, smelt, silversides, shiner surfperch and small crustaceans.

Nesting: The Least Tern arrives at its breeding grounds in late April. The breeding colonies are not dense and may appear along either marine or estuarine shores, or on sand bar islands in large rivers, in areas free from humans or predators. Courtship typically takes place removed from the nesting colony site, usually on an exposed tidal flat or beach. Only after courtship has confirmed mate selection does nesting begin by mid-May and is usually complete by mid-June. Nests are situated on barren to sparsely vegetated places near water, normally on sandy or gravelly substrates. In the southeastern United States, many breeding sites are on white gravel rooftops. In the San Francisco Bay region, breeding typically takes place on abandoned salt flats. Where the surface is hard, this species may use an artificial indentation (such as a deep dried footprint) to form the nest basin.

The nest density may be as low as several per acre, but in San Diego County, densities of 200 nests per acre have been observed. Most commonly the clutch size is two or three, but it is not rare to consist of either one or four eggs. Both female and male incubate the eggs for a period of about three weeks, and both parents tend the semiprecocial young. Young birds can fly at age four weeks. After formation of the new families, groupings of birds may appear at lacustrine settings in proximity to the coast. Late season nesting may be renests or late season arrival activity. In any case, the bulk of the population has left the breeding grounds by the end of August.

Cool Facts: The Least Tern hunts primarily in shallow estuaries and lagoons, where smaller fishes are abundant. They hover until spotting prey, and then plunge into the water without full submersion to extract dinner.


Found in Songbird ReMix Seabirds 1

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