(Phaethon rubricauda)
Hawaiian Name: Koa‘e‘ula
The Red-tailed Tropicbird is a wide-ranging seabird found across most of the tropical and subtropical Indian and Pacific Oceans, but are absent from the Atlantic Ocean. In Hawaiʻi, an estimated 13,000 pairs are found breeding across all of islands in the Northwestern Chain , and 980 pairs are found spread amongst very small (but increasing) colonies on all of the Southeastern Hawaiian Islands.
On Kauaʻi, a small but growing colony is found at Kilauea Point NWR where they are usually very conspicuous during the breeding season from February to October. Especially early in the breeding season they can be seen courting in small groups, which consists of two to several birds performing impressive vertical, backwards summersaulting circles, all the while emitting harsh squawks. The nest is a simple scrape in the ground, usually in the shade under a tree or bush. The species appears to be relatively unaffected by non-native vegetation, and the primary nest predator appears to be rats, although cats are certainly capable of taking adults and nestlings. Outside of Hawaiʻi, humans also collect nestlings for food, especially at some south Pacific islands. With the increased protection of colonies in Hawaiʻi, the Hawaiian populations of Red-tailed Tropicbirds have expanded greatly since the 1950’s.
Red-tails nest in small loose colonies, but are otherwise completely solitary. At sea they fly high over the water before plunging down into the water to catch fish and squid, and at least in Hawaiʻi most of their diet appears to be flying fish. However, not much is known about their habits at sea. In the nonbreeding season individuals are found far out at sea fairly evenly dispersed across much of the Pacific and Indian Oceans, although there appears to be some dispersal to temperate areas during this time.
Superficially similar to the closely related White-tailed Tropicbird, this species can be identified by its red tail streamers, larger size, bright red bill, and nearly solidly white body and wings. Especially on Kauaʻi it is very unlikely to see it over land anywhere away from the one colony at Kilauea Point. Most other sightings come from boats at least a few miles away from the island, and overall it is much less common than the ubiquitous White-tailed Tropicbird.
Kauaʻi Endangered Seabird Recovery Project 