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Identificazione

The adult white-tailed tropicbird is a slender, mainly white bird, 71–80 cm long including the very long central tail feathers, which double its total length. The wingspan is 89–96 cm. The bird has a black band on the inner wing, a black eye-mask, and an orange-yellow to orange-red bill. The bill colour, pure white back and black wing bar distinguish this species from the red-billed tropicbird.<p>The white-tailed tropicbird breeds on tropical islands, laying a single egg directly onto the ground or a cliff ledge. It disperses widely across the oceans when not breeding, and sometimes wanders far. It feeds on fish and squid, caught by surface plunging, but this species is a poor swimmer. The call is a high screamed keee-keee-krrrt-krrt-krrt. Sexes are similar, although males on average are longer tailed, but juveniles lack the tail streamers, have a green-yellow bill, and a finely barred back. The white-tailed tropicbird does not have a yearly breeding cycle; instead, breeding frequency depends on the climate and availability of suitable breeding sites. The bird can reproduce 10 months after the last successful breeding, or 5 months after an unsuccessful one.

Tassonomia

French zoologist François Marie Daudin described the white-tailed tropicbird in 1802.<p>"White-tailed tropicbird" has been designated the official name by the International Ornithologists' Union (IOC).<p>Its closest relative is the red-tailed tropicbird (P. rubricauda), the split between their ancestors taking place about four million years ago.<p>Six subspecies are recognised by the IOC:

Nome scientifico

Phaethon lepturus

Autorità

Daudin, 1802

Ordine

Phaethontiformes

Famiglia

Phaethontidae

Genere

Phaethon

Areale e habitat

Areale riproduttivo

TrO : widespread all tropical oceans (except e Pacific and ne Atlantic)

Areale non riproduttivo

pelagic; to waters off e Africa, w, s Sri Lanka (w, n Indian Ocean), Indonesian Arch. and New Guinea waters, ec Australia (sw South Pacific) and Gulf Stream n to North Carolina (w North Atlantic)

Migrazione

Complete migrants

Comportamento

The white-tailed tropicbird feeds mainly on flying fish, squid and crabs. It catches its prey by diving from height of up to 20 meters, as do gannets. However, flying fish are caught in flight. It usually feeds in pairs. Prey is often detected by hovering above the surface as the bird swallows it before taking off.

Conservazione

Population trends are unknown. In Mexico it is not under any category of protection, and no specific conservation programs for these tropicbirds are known. However, the species is found in various conservation programs as an American waterfowl. It is recommended to conduct studies on the biology of this species at sea, as well as monitoring of breeding colonies. Globally it is considered a species of Least Concern.

Tendenza della popolazione

declining