American Little Tern

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American Little Tern
American Little Tern

American Little Tern

Systematics
Class : Birds (aves)
Order : Plover-like (Charadriiformes)
Family : Terns (Sternidae)
Genre : Sternula
Type : American Little Tern
Scientific name
Sternula antillarum
( Lesson , 1847)

The American little tern ( Sternula antillarum ) is a species of bird in the family of the tern (Sternidae). In appearance it resembles its European relative, the little tern ( Sternula albifrons ), but differs from it mainly in its vocalizations. With a length of 22-24 centimeters and a wingspan of 51 centimeters, it is one of the smallest terns.

Appearance

The adult little tern's beak is yellow with a black tip. The underside of the plumage is white, the upper side gray. The outermost two - more rarely three or four - hand wings are colored black. The white plumage of the forehead contrasts with the black color of the rein strip, crown and neck. The legs are yellow to orange, sometimes with a grayish or pale pink tint. There is hardly any difference in appearance between male and female animals , so sex can most likely be determined through behavior.

Subspecies and distribution

The number of subspecies is controversial. Gochfeld and Burger recognize three subspecies:

  • S. a. browni (Mearns, 1916) - Along the Pacific coast from San Francisco Bay to Baja California , as well as in western and southern Mexico ; overwinters mostly along the western and southern coast of Mexico.
  • S. a. athalassos (Burleigh & Lowery, 1942) - Along rivers in inland North America, from the northern Great Plains to Texas and northern Louisiana ; winters in northern Brazil .
  • S. a. antillarum Lesson, 1847 - On the American east coast from Maine to Texas and as far as Honduras and through the Caribbean to northern Venezuela ; winters in northern Brazil .

Way of life

Food acquisition and food

Fish are the main food source of the American little tern.

The diet of the American little tern consists mainly of small fresh or saltwater fish , but also of crustaceans and insects . When foraging for food, the birds prefer shallow waters such as bays , lagoons , sea ​​marshes or rivers. The American Little Tern spies its prey from about 1 to 10 meters above the surface of the water when it comes to food, and usually prey on it by diving . The animals usually get food only a few 100 meters away from the colony.

Reproduction and breeding

American little tern with its two day old chick

The American Little Tern breeds along sandy beaches and larger rivers in North America and winters on the coasts of Central and South America . The breeding colonies usually contain 5 to 200 pairs, but can sometimes exceed 3,000 pairs. The typical clutch consists of two to three eggs, which are laid in a simple sand or gravel hollow. The young birds hatch after 19 to 24 days of breeding, and they will be able to fly after another three weeks.

Migratory behavior

The American little tern is a long-distance migrant . It leaves its breeding grounds in late summer or early autumn and moves to Central and South America in their wintering areas. The birds join together in small, loose groups and follow rivers and coastlines whenever possible to acquire food. As they migrate back to the breeding grounds in the north, the birds reach the Gulf Coast of Mexico , Georgia, and South Carolina between March and April, California and Kentucky in April, New York and Massachusetts between April and May, and Illinois and Iowa in May.

Existence and endangerment

In the late 19th and early 20th centuries, stocks declined threateningly, mainly due to the strong demand for bird feathers for women's hats and the collection of eggs for human consumption. Today, the greatest threat to the American Little Tern is the restriction of its breeding area as sandy beaches in North America are exposed to a variety of human influences. However, due to its extremely wide range and high population numbers, the species is classified as not endangered by the IUCN .

literature

  • M. Gochfeld / J. Burger: Least Tern (Sternula antillarum) , in: J. del Hoyo / A. Elliott / J. Sargatal / DA Christie / E. de Juana (eds.), Handbook of the Birds of the World Alive , Barcelona 2014 (last accessed December 14, 2015).
  • Bruce C. Thompson / Jerome A. Jackson / Joanna Burger / Laura A. Hill / Eileen M. Kirsch / Jonathan L. Atwood: Least Tern (Sternula antillarum) , in: A. Poole (Eds.), The Birds of North America Online, Ithaca 1997, doi : 10.2173 / bna.290 (last accessed December 14, 2015).

Web links

Commons : Sternula antillarum  - Collection of images, videos and audio files