Least Tern (LETE)

Sternula antillarum

Adult Least Tern © Liam Wolff / Macaulay Library
Juvenile Least Tern © Harlan Stewart / Macaulay Library

Least Tern populations are concentrated along ocean coasts from North America to the top of South America; they can also be found in some inland locations

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Identification

This species is the smallest of all North American terns, about 22 cm in length. They have a black cap and stripe over the eye, which contrasts with the white forehead, neck, and underbelly. The upperparts and wings are light gray, and the straight, narrow bill is yellow or orange with a dark tip. The black stripe over the eye is considered wider on male Least Terns but sexes are more reliably distinguishable by behavior.

The Least Tern has calls but does not have a song. These calls include vocalizations like ki-dik for the male’s contact call, alarm calls such as zweep, tsip tsip tsip, kit-kit-kit-kit, or krowkgh, recognition calls like k’ee-you-hud-dut, keedee-cui keedee-cui, or kee-zink kee-zinkI. Other calls include the k’ee-you summons call to their young and the throaty brooding call between mates.

Listen to its calls here.

Habitat

Least Terns typically form colonies along coasts or rivers on sand or dried mudflats with little to no vegetation. They can also be found on sandy or shell islands, as well as on gravel and sand pits. Their nests are often on deposited dredged materials, such as sand, silt, or gravel. On Long Island, New York, Least Terns usually use habitats like peninsulas, sandy shorelines, and barrier islands.

Conservation Status 

Status by State

Threats to Conservation

Least Tern populations are affected by flooding, habitat destruction, nest-disturbance, and pollution. Pollutions of particular concern include PCBs, pesticides such as DDT, and heavy metals because these can accumulate in birds with a primary diet of fish. Oil pollution is also an issue in coastal and inland habitats as well as on migration routes. Least Terns are also affected by human disruption through shoreline development, depositing of dredged material, water turbulence from jet skis/boats, and nest disturbances from pedestrians. 

Funding Opportunities
General Management Guides
Regional Management Guides
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Works Cited