page_title: Tern
section_title: Predators and parasites
hierarchical_section_title: Tern / Predators and parasites
caption_attribution_description: Feeding Frenzy in Windy Cove today included about fifty or more Elegant Terns diving for Anchovies, Pelicans and Western Gulls included. The Western Gulls aggressively tried to get the Terns to drop their catch.
context_page_description: Terns are seabirds in the family Laridae that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated as a subgroup of the family Laridae which includes gulls and skimmers and consist of eleven genera. They are slender, lightly built birds with long, forked tails, narrow wings, long bills, and relatively short legs. Most species are pale grey above and white below, with a contrasting black cap to the head, but the marsh terns, the Inca tern, and some noddies have dark plumage for at least part of the year. The sexes are identical in appearance, but young birds are readily distinguishable from adults. Terns have a non-breeding plumage, which usually involves a white forehead and much-reduced black cap.
  The terns are birds of open habitats that typically breed in noisy colonies and lay their eggs on bare ground with little or no nest material. Marsh terns construct floating nests from the vegetation in their wetland habitats, and a few species build simple nests in trees, on cliffs or in crevices. The white tern, uniquely, lays its single egg on a bare tree branch. Depending on the species, one to three eggs make up the clutch.
context_section_description: The inaccessibility of many tern colonies gave them a measure of protection from mammalian predators, especially on islands, but introduced species brought by humans can seriously affect breeding birds. These can be predators such as foxes, raccoons, cats and rats, or animals that destroy the habitat, including rabbits, goats and pigs. Problems arise not only on formerly mammal-free islands, as in New Zealand, but also where an alien carnivore, such as the American mink in Scotland, presents an unfamiliar threat.
  Adult terns may be hunted by owls and raptors, and their chicks and eggs may be taken by herons, crows or gulls. Less obvious nest predators include ruddy turnstones in the Arctic, and gull-billed terns in little tern colonies. Adults may be robbed of their catch by avian kleptoparasites such as frigatebirds, skuas, other terns or large gulls.
  External parasites include chewing lice of the genus Saemundssonia, feather lice and fleas such as Ceratophyllus borealis. Lice are often host specific, and the closely related common and Arctic terns carry quite different species. Internal parasites include the crustacean Reighardia sternae, and tapeworms such as Ligula intestinalis and members of the genera Diphyllobothrium and Schistocephalus. Terns are normally free of blood parasites, unlike gulls that often carry Haemoproteus species. An exception is the brown noddy, which sometimes harbours protozoa of that genus. In 1961 the common tern was the first wild bird species identified as being infected with avian influenza, the H5N3 variant being found in an outbreak involving South African birds. Several species of terns have been implicated as carriers of West Nile virus.
caption: Kleptoparasitic western gull chasing elegant tern
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