The largest of all terns (up to 56 cm length) the powerful Caspian Tern occurs throughout most of the world; however, South American records pertain to wintering birds. They may be encountered on lakes, rivers, and seacoasts, frequently mixing with gulls or other species of terns. Colonies of this adaptable species may be immense (over 10,000 nesting pairs) and are often established on artificial substrates such as islands of dredge material. When food is plentiful, a clutch consists of three eggs. Identification is usually straightforward beginning, if possible, with a size comparison with nearby birds. Note the Caspian’s dark cap which, unlike other terns, is retained through the non-breeding season, long and thick red bill, black feet and legs, white underparts, pearly gray upperparts, and, in flight, the blackish wash to the underside of the primaries. Sexes are alike. Young birds have a speckled crown and black marks on the mantle. The Caspian’s grating kraaaa call is useful identification characteristic.