The tropicbirds can remain at sea for an indefinite time (4) (5). These birds fly with rapid wing-beats and can also exploit their long wingspan and streamlined body shape to attain impressive altitudes by soaring upwards on rising thermals. While resting at sea, the 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 (4).
The red-tailed tropicbird feeds largely on flying fish and squid (2) (4). Once prey is targeted, it hovers briefly in the air with the head and bill pointed downwards, before making a rapid, vertical, spiralling plunge into the water from 15 to 20 metres height (2) (4) (5). In the water, this bird can make rapid movements, with quick turns and twists, using the half-bent wings to control its body, before capturing its prey in its serrated beak. Flying fish may also be caught in flight as they flee from feeding tuna below them, and the red-tailed tropicbird may seek out fish that have been flushed by boats or, more rarely, shoals of hunting tuna. On land, however, this bird is less impressive and movement is extremely awkward. The bird lies on its belly, pushes with its feet, and flops onto the belly again to make its way forward. At times it will even stab its bill into the ground to pull itself forward (4).
At sea, the red-tailed tropicbird is largely solitary, but during the breeding season they tend to nest in loose colonies (2) (4) (5) (6). Prior to breeding, mature birds engage in unusual, aerial courtship displays, with up to 15 birds flying upwards in wide circles, all the while emitting harsh squawks, before monogamous partners pair up (4) (6). Nesting areas are defended against intruders and there may be fierce competition for the best nesting sites in a crowded colony where bloody fights between birds may ensue, with stabbing, slashing and the interlocking of bills (4). A nest scrape is created by the male on the ground under a bush or shrub that offers shelter from the sun (2) (4) (5). A single egg is laid, and incubated alternately by the male and female for some 42 to 46 days. Once hatched, both adults feed the chick until it fledges at 67 to 91 days of age, with the length of time to fledging varying with the quantity of the food supply that year (2) (6). During the non-breeding season juveniles and adults wander the ocean as far as 5,000 kilometres from their nesting colony (2). Birds first breed at 2 to 5 years of age and will return to the same colony to nest each year (4).