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Breeding adult. Photo: Dieter Schonwetter/Audubon Photography Awards

Forster's Tern

Sterna forsteri

Several of the terns are very similar in appearance. Forster's Tern looks so much like a Common Tern that it was largely overlooked by Audubon and other pioneer birders. However, Forster's is more of a marsh bird at most seasons, especially in summer, when it often nests on top of muskrat houses. Unlike Common Tern, Forster's regularly winters along our southern coasts.

Conservation status	Has declined in some areas with loss or degradation of marsh habitat. Recreational boating on nesting lakes may have impact as well, since wakes from speedboats often flood nests.
Family	Gulls and Terns
Habitat	Marshes (fresh or salt), lakes, bays, beaches. During summer is mostly around marshes, either coastal salt marsh or large marshy lakes in the interior. May visit any waters during migration. Winters mostly along coast, especially around estuaries, inlets, coastal lagoons, sheltered bays.

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Feeding Behavior

Forages by flying and hovering over water, plunging to take fish from just below surface. Also may dip down in flight to take items from surface, and will forage in the air, catching insects in flight.

Eggs

3, sometimes 1-4. Olive to buff, variably marked with brown. Incubation is by both sexes, 23-25 days. Young: Both parents feed young in nest. Development of young and age at first flight not well known.

Young

Both parents feed young in nest. Development of young and age at first flight not well known.

Diet

Fish, insects, other small aquatic life. Diet is mostly fish at all seasons, but in summer on marshes may eat many insects. Also eats small crustaceans, frogs.

Nesting

May breed in loose colonies, with spacing dictated by arrangement of good nesting sites. Sometimes associated with colonies of Yellow-headed Blackbird. Aggressive toward other birds in vicinity of nest. Nest site is in marsh, on top of dense vegetation or mats of floating dead plants, often on top of muskrat house. Sometimes placed on ground near marsh, or on abandoned nest of grebe. Where it nests in same marsh as Black Tern, Forster's tends to choose higher and drier nest sites. Nest (built by both sexes) is platform of reeds and grasses, with deep hollow at center lined with finer material and shells.

Illustration © David Allen Sibley.
Learn more about these drawings.

Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

Much less migratory than Common Tern, wintering regularly along southern coastlines of United States.

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Migration

Much less migratory than Common Tern, wintering regularly along southern coastlines of United States.

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

Songs and Calls

Harsh nasal beep.

Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Forster's Tern

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.

Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.

Climate threats facing the Forster's Tern

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.