Colony Site Selection of Short-tailed Shearwaters in Tasmania.

Highly pelagic seabirds are generally inefficient at taking off and landing at their breeding grounds. The Procellariidae in particular have evolved efficient gliding flight and a modest ability at diving and underwater swimming (Kuroda 1954, Warham 1977, 1990, Skira 1979, Oka 1994). The adaptive changes in their flight musculature and wing and body structure have given rise to a reduction in ease of movement on land. To facilitate taking off from land, they are known to make use of local winds and the assistance of cliffs, slopes, rocks (Warham et al. 1982) or trees (Yoshida 1962, Jida et al. 1987) to launch themselves into flight. The Short-tailed Shearwater, a smaller species of the genus Puffinus, often uses special departure rocks for wind-assisted launches (Warham 1960). Notwithstanding its lack of maneuverability and susceptibility to predation on land, this species maintains a large population estimated to be 23 million breeders (Skira et al. 1985) and a wide pelagic range in the Pacific Ocean (Shuntov 1972, Marchant and Higgins 1990). About 80% of the shearwaters were estimated to breed in Tasmania. To understand more about the terrestorial adaptations and colony site selection of this species, we examined the topography of it colonies in Tasmania.