Guide to North American Birds
Conservation status North American population has declined sharply since the 1960s. Loss of nesting habitat owing to drainage of wetlands is one likely cause. Runoff of farm chemicals into nesting marshes may affect hatching success. Loss of food supply on the wintering grounds, owing to local overfishing, may also be a factor.
Family Gulls and Terns
Habitat Fresh marshes, lakes; in migration, coastal waters. For nesting favors fresh waters with extensive marsh vegetation and open water, also sometimes in smaller marshes and wet meadows. In migration found on larger lakes and along coast. Winters in tropical coastal regions, mostly just offshore or around salt lagoons and estuaries.
A small, graceful marsh tern, black and silver in breeding plumage. In its choice of surroundings, it leads a double life: in North America in summer it is a typical bird of freshwater marshes, but in winter it becomes a seabird along tropical coasts. Vulnerable to loss of marsh habitat, its numbers have decreased in many areas during recent decades.

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Feeding Behavior

Forages in flight, dipping to surface of water or shore to pick up items, sometimes pursuing flying insects in the air, seldom plunging into water after prey.


Eggs

2-4. Pale buff to olive, blotched with brown and black. Incubation is by both sexes, 21-22 days. Young: Develop rapidly; after 2-3 days, may leave nest but remain in vegetation nearby. Capable of flight 19-25 days after hatching; may be fed by parents for up to two more weeks. One brood per year, sometimes two in south.


Young

Develop rapidly; after 2-3 days, may leave nest but remain in vegetation nearby. Capable of flight 19-25 days after hatching; may be fed by parents for up to two more weeks. One brood per year, sometimes two in south.

Diet

Mostly insects, fish. Diet on breeding grounds is mostly insects, also small fish, tadpoles, frogs, spiders, earthworms, crustaceans, leeches. In migration and winter at sea, eats mostly small fish, also some crustaceans and insects.


Nesting

Breeds in scattered colonies, often associated with Forster's Terns. Early in season, pairs or small groups ascend in spiraling high flight above colony, then glide down. Nest site is low in marsh, on floating mat of plant material, on old muskrat house or debris, or on ground close to water. Nest (built by both parents) may be substantial platform of marsh plants, or simple depression with a few bits of vegetation added, very close to water level; eggs often damp.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

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Migration

Most apparently migrate north through interior of North America. In late summer, many move east to Atlantic Coast before turning south; those from farther west may move south to coasts of Mexico and continue southward offshore. Winters mostly along north and northwest coasts of South America.

  • All Seasons - Common
  • All Seasons - Uncommon
  • Breeding - Common
  • Breeding - Uncommon
  • Winter - Common
  • Winter - Uncommon
  • Migration - Common
  • Migration - Uncommon

See a fully interactive migration map for this species on the Bird Migration Explorer.

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Songs and Calls

Sharp kick; when disturbed, a shrill kreek.
Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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