Forster's Tern (Birds of the Alameda Shoreline )

Forster's Tern

Sterna forsteri

Summary ⁴

The Forster's Tern (Sterna forsteri) is a member of the tern family Sternidae. It breeds inland in North America and winters south to the Caribbean and northern South America.

Physical description ⁵

Forster's terns are medium-sized birds. They are mostly white, with a pale gray back and wings and a black cap. They have long tails that form a deep “V” shape, and their outer tail feathers are long, like streamers. Their legs are orange, and their bills are orange with a black tip.

In winter, Forster’s terns do not have a black cap. Instead, they have a black mark behind each eye. Male and female Forster’s terns look the same. They weigh 130 to 190 g, and are 33 to 36 cm long. Young Forster’s terns look like adults, but have darker wing feathers.

Range mass: 130 to 190 g.

Range length: 33 to 36 cm.

Sexual Dimorphism: sexes alike

Food habits ⁶

Forster's terns eat many species of small fish, arthropods and occasionally frogs.

Forster's terns hunt by flying back and forth over the water with their bill pointing downward and their feet folded against their body. They typically fly about 6 to 8 m above water. When they spot prey, they either plunge directly into the water toward the prey or hover briefly before diving. They occasionally hunt from perches, such as posts, bridges and telephone wires.

Animal Foods: amphibians; fish; insects

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)

Habitat ⁷

Forster's terns are found in fresh, brackish, and saltwater marshes, including marshy borders along lakes, islands, and streams.

Habitat Regions: temperate ; terrestrial ; saltwater or marine ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal ; brackish water

Wetlands: marsh

Other Habitat Features: estuarine

Lifespan/longevity ⁸

Not much is known about the lifespan of Forster's terns. The oldest banded Forster's tern on record was 12 years old when it died.

Range lifespan
Status: wild: 12 (high) years.

Average lifespan
Status: wild: 190 months.

Sources and Credits

(c) Dick Daniels (http://carolinabirds.org/), some rights reserved (CC BY-SA), https://upload.wikimedia.org/wikipedia/commons/a/a8/Forster%27s_Tern_%28Sterna_forsteri%29_RWD1.jpg
(c) Mike Baird, some rights reserved (CC BY), http://www.flickr.com/photos/72825507@N00/3066143123
(c) Alan Vernon, some rights reserved (CC BY), https://upload.wikimedia.org/wikipedia/commons/1/1a/Forster%27s_Tern_Bolsa_Chica.jpg
Adapted by Marisa Rafter from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Sterna_forsteri
(c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25067074
(c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18674373
(c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25067073
(c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25067077