Red-tailed Tropicbird

The red-tailed tropicbird measures 95 to 104 cm (37 to 41 in) on average, which includes the 35 cm (14 in) tail streamers, and weighs around 800 g (30 oz). It has a wingspan of 111 to 119 cm (44 to 47 in). It has a streamlined but solid build with almost all-white plumage, often with a pink tinge. The sexes are similar in plumage. A dark brown comma-shaped stripe extends back from the lores, through and over the eyes and reaching the ear coverts. The iris is dark brown. The bill is bright red, slightly paler at the base and black around the nostrils. The legs and base of the toes are pale blue-mauve, while the webbing and rest of the toes are black. The white feathers of the head and rump have concealed dark brown bases, while those of the mantle, back, tail rectrices and tail coverts have dark brown shaft bases. The two long tail feathers are orange or red with white bases for around a tenth of their length, and can be hard to see when the bird is flying. The white wings are marked by dark chevron-shaped patches on the tertials, and the dark shafts of the primary flight feathers are visible. The pink tinge is often more pronounced in the remiges of the upper wing. Moulting takes place outside the breeding season, the streamers being replaced before the rest of the feathers. …

The red-tailed tropicbird ranges across the southern Indian, and western and central Pacific Oceans, from the East African coast to Indonesia, the waters around the southern reaches of Japan, across to Chile, and the Hawaiian Islands, where they are more common on the northwestern islands. It frequents areas of ocean with water temperatures from 24 to 30 °C (75 to 86 °F) and salinity under 35% in the southern hemisphere and 33.5% in the northern hemisphere. In the Pacific Ocean, the southern boundary of its range runs along the 22 °C (72 °F) summer surface isotherm. The birds disperse widely after breeding. Evidence suggests birds in the Indian Ocean follow prevailing winds westwards, young individuals banded in Sumatra and Sugarloaf Rock, Western Australia, being recovered at Mauritius and Réunion respectively. Banding on Kure Atoll suggests birds in the North Pacific disperse in an easterly direction, following prevailing winds there. Strong winds can blow them inland on occasions, which explains some sighting records away from the coast and their preferred habitats. Johnston Atoll It is the world's largest colony of red-tailed tropicbirds, with 10,800 nests in 2020. In the Pacific area, it nests on the Australian offshore territories of Norfolk and Lord Howe Islands, and on Queensland's coral islands (including Raine Island and Lady Elliot Island). …

The red-tailed tropicbird is a strong flyer, and walks on land with difficulty using a shuffling gait. They can hover in midair by flying into the wind; pairs may even fly backwards and circle each other during courtship displays.

Breeding. The red-tailed tropicbird is thought to be monogamous, pairs remaining bonded over successive breeding seasons, although such information as age at first breeding and pair-formation is not known. It nests in loose colonies, on offshore islands and stacks, rocky cliffs, coral atolls and cays. It rarely nests on large bodies of land, though has done so in southern Western Australia. The nest itself is a shallow scrape, in either shaded sand or a rocky crevice, or under a shrub. Because the red-tailed tropicbird does not walk well, it lands by flying into the wind, stalling and dropping to the ground. The nest is often located within one metre (3.3 ft) of the edge of the shrub (or other shaded area) to minimise walking distance. The tropicbird often chooses shrubs with fewer stems for accessibility.

The species is territorial to a degree, aggressively defending the nest site and pecking radius around it, commencing around three months before breeding. Birds are more aggressive at crowded colonies, where numbers are large or suitable nest sites less common. …