Snowy-crowned tern

The snowy-crowned tern (Sterna trudeaui), also known as Trudeau's tern, is a species of bird in subfamily Sterninae of the family Laridae, the gulls, terns, and skimmers. It is native to Argentina, Brazil, Chile, Uruguay, and possibly Paraguay, and also vagrant in Peru and the Falkland Islands.

The snowy-crowned tern is 28 to 35 cm (11 to 14 in) long with a wingspan of 76 to 78 cm (30 to 31 in) and weighs 146 to 160 g (5.1 to 5.6 oz). It has a rather blocky head, a thick neck, long wings, and a forked tail. The sexes have the same plumage. Adults in breeding plumage have a white head and neck with a black band through the eye. Their upperparts are pale gray with a whitish rump and uppertail coverts. Their underparts are grayish white. Their upperwing is pale gray with silvery primaries and the underwing is white. Their iris is brown and their bill orange with a yellow tip and a black band separating the colors. Their legs and feet are reddish orange. Non-breeding adults are similar to breeding ones, but with a grayer stripe on the face, more intense silvery on the primaries, and a black bill with a yellowish tip. Juveniles have a black and white pattern on their back, a black band near the end of the tail, a black bill, and dark legs.