SUMMARYTarburton, M. K. 1977. Nesting of the Red-tailed Tropicbird at Sugarloaf Rock, WA. Emu 77: 122–126. Records of the Red-tailed Tropicbird in southern Western Australia before regular nesting began at Sugar- loaf Rock are given. The growth of the colony and its situation are described. Aerial displays and choice of nesting sites were observed. The incubation period was forty-one to forty-eight days. Pair-bonding and attachment to nest site are common. The nesting season extended from October to June but was concentrated mostly in December, January and February. Mortality was high in all seasons during the study. Food of the birds was noted from regurgitated material.