chin, throat and underparts, and prominent black barring and scaling on their crown, nape, mantle, back, rump and upper wing coverts. Their bills are blackish grey with a light blue-grey base, and grey legs and feet. In Australian waters the red-tailed tropicbird could be confused with the silver gull (Chroicocephalus novaehollandiae) or various tern species, though it is larger and heavier-set, with a wedge-shaped tail. Its red bill and more wholly white wings distinguish it from the adult white-tailed tropicbird. Immature red-tailed tropicbirds likewise can be distinguished from immature white-tailed tropicbirds by their partly red rather than yellow bills. The red-tailed tropicbird is generally silent while flying. Aside from during courtship displays, birds may give a short greeting squawk to their mate when arriving or leaving the nest. Birds give a low growling call as a defence call, and young chatter repetitively as a begging call—made whenever the parents are nearby. Distribution and habitat 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 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 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). In mid-2020 Australian scientists found a bird on Lady Elliott Island that they had banded 23 years earlier as a chick, but had not seen since, which had come back to breed on the island. In New Zealand territory it breeds on the