Census and Distribution of Wedge-tailed Shearwater Puffinus pacificus Burrows on Heron Island, November 1985

Abstract

A census of Wedge-tailed Shearwater nesting density on Heron Island in 1985 returned an estimate of 16 337 ± 1545 (X ± s.e.) active burrows, an increase of over 147% on the most recent previous survey conducted in 1983. A similar survey of nearby Masthead Island indicated a decrease of around 35% over the same period. An assessment of habitat usage on Heron Island indicated that shearwaters utilise all vegetation types found on the island. Highest densities were recorded in disturbed habitats with a ground cover of Pisonia branches or building material debris. Our findings are contrary to previous assessments that closed Pisonia forest is the preferred nesting habitat. As well, there was no significant difference in burrow density between the eastern (national park) and western (resort, research station) halves of the island. Loss of breeding sites in the western section, resulting from construction of facilities, was balanced by the higher availability of the preferred, disturbed, habitats which were also a result of human activities.