southern Pacific Ocean, including populations on the Cook Islands, Tonga, Samoa, the Marquesas and the Society Islands. The ornithologist Mike Tarburton reviewed the known subspecies in 1989 and concluded that none were valid, noting that there was a clinal change in size in the species: those from Kure Atoll in the North Pacific being the smallest; ranging to those from the Kermadec Islands in the South Pacific being the largest. He also noted that the pink colouration was more intense in new plumage and faded after a few years in museum specimens. Description The red-tailed tropicbird measures on average, which includes the , and weighs around . It has a wingspan of . 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. Streamers are replaced at any time, one growing while the other is shed, and old streamers may litter the area around a breeding colony. Newly hatched chicks are covered in thin, long, grey-white down, which is paler on the head. The lores are bare. The down is greyer in older chicks. The primaries, rectrices and scapulars are evident in the third week, and chicks are mostly feathered with residual down on underparts and under the wings after six weeks, and fully feathered by 11 weeks. Juvenile birds have a glossy white forehead,