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White-tailed Tropicbird

Phaethon lepturus dorotheae / Koa‘e‘kea
White tailed tropicbird

The white-tailed tropicbird is the smallest of the tropicbirds, a group of elegant seabirds renowned for their greatly elongated tail streamers that extend from the wedge-shaped tail. Adult birds have mostly white plumage with long, white tail streamers. Tail feathers are visible while the bird is in flight as compared to the koa‘e ‘ula. Black eye-stripe from gape curving toward and passing through eye. Diagonal black stripe across upper wings. Yellowish to orange bill. Legs/feet are yellowish with black webs.

Tropicbirds are remarkable for being able to remain at sea for indefinite periods, and can sustain long periods of flight. While resting at sea, tropicbirds float on the sea surface, due to their fully waterproof plumage, and will take to the air again after powerful beats of the wings and thrusts of the fully-webbed feet.

Once its prey is targeted, it hovers briefly with the head and bill pointed downwards, before making a rapid, vertical, spiraling plunge. With folded wings, koa‘e kea hit the water and completely submerge to seize and swallow prey before flight. In the water, this bird can make rapid movements, with quick turns and twists, all the while using the half-bent wings to control its body, and its prey is captured in its serrated beak. On land, however, this bird is less impressive and movement is extremely awkward. The bird lies on its belly and stabs its bill into the ground, pulling itself forward in an ungainly shuffle.

Prior to breeding, monogamous pairs engage in unusual courtship displays, with up to 20 birds flying with ritualized wingbeats, dives and calls. The birds fly in unison, make wide circles and drop the tail and streamers in an arc, before pairs leave the group and perform a descending glide or zigzag in tandem.

A nest is created by the male in a rocky crevice that offers some shelter from the sun, or less favorably on the ground. A single egg is laid and incubated by both the male and female at intervals of 13 days for some 40 to 43 days. Once hatched, the chick is largely left alone in the nest while the parents forage out at sea. It is at this time that the chick is most vulnerable to attacks, particularly from adults of the same or different species, which are looking for nesting sites. The single chick fledges after 70 to 85 days in the nest, and may join the adults in undertaking nomadic movements that see the birds wander as far as 1,000 kilometers out to sea in search of favorable feeding grounds . The white-tailed tropicbird first breeds between two and five, with most birds breeding in their third or fourth year.

Facts About White-tailed Tropicbird

Diet
Feeds largely on flying fish, but may supplement this diet with squid and crustaceans.
Life Span
16 years
Size
Length: 38-40 cm (15-16 in), 71-81 cm (28-32 in), including tail streamers; wingspan: 90-95 cm (35-37 in) 
Page Photo Credits — USFWS
Last Updated: Aug 29, 2013
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