There are six subspecies:
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, and there is a black band on the inner wing There is black through the eye and the bill is orange-yellow to orange red. The bill colour, pure white back and black wing bar distinguish this species from red-billed. 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 average 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.
White-tailed tropicbird feeds mainly on flying fish, squid and crabs. It catches its preys by diving from height of up to 20 meters, as gannets. However, flying fish is caught in flight. It usually feeds sometimes in pairs. Prey is often detected by hovering above the surface as the bird swallows it before to take off.
Although their population trends are unknown. In Mexico it is not under some category of protection and no specific conservation programs for these tropicbird are known, the species is found in various conservation programs as the 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.
The ancient Chamorro people called the white-tailed tropicbird utak or itak, and believed that when it would scream over a house it meant that someone would soon die or that an unmarried girl was pregnant. Its call would kill anyone who didn't believe in it. Chamorro fishermen would find schools of fish by watching them.