Biology Of Terns
Terns are slender birds with long, pointed wings, and are adept fliers. Their tail is usually forked to some degree, and their bill is sharply pointed. The usual coloration is some combination of white, gray, and/or black.
The smallest species is the little tern (Sterna albifrons), which is only 9 in (23 cm) in body length and 1.8 oz (50 g) in weight. The largest species is the Caspian tern (Hydroprogne caspia), which is 20 in (50 cm) long, and weighs 25 oz (700 g).
Most terns feed on fish, small squid, or large invertebrates. Species occurring in freshwater habitats may also eat amphibians and large insects. Terns typically hunt their aquatic prey by plunging head-first into water, often after having located their quarry by briefly hovering.
Terns typically nest in colonies, some of which are large. The usual nesting locale is a gravel shore, generally on an island or relatively isolated peninsula. The typical nest built by terns is a simple scrape, but tropical terns known as noddies (Anous spp.) build a more substantial nest in a tree or on cliff ledges. Some fairy terns do not build a nest at all—they lay a single egg, wedged into the fork between two branches of a tree.
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