The effects of human activities on shorebirds, seabirds and waterbirds of Comerong Island, at the mouth of the Shoalhaven River.

Abstract

Comerong Island is a 660 ha Nature Reserve 15 km east of Nowra. The island sits at the mouth of the Shoalhaven River estuary (Fig. 1) and is the fifth most important area for shorebirds or waders in New South Wales (Morris 1983, Lane 1987). Ninety species of shorebirds or waders (Charadriformes), waterbirds (including ducks, rails, herons, ibises and cormorants) and seabirds have been recorded on the island (Appendix 1). Up to 7000 ducks and 1200 other waterbirds have been counted on the estuary (Chafer pers. Comm.). I will concentrate mostly on shorebirds as these are more restricted to estuarine habitats. Table 1 lists relative abundance for some of these species. Nearly half the Double-banded Plovers Chadradrius bicintus and almost a quarter of the Red-necked Stints Calidris ruficollis found on estuaries within New South Wales are found on Comerong Island. There is little doubt that habitat changes and loss of wetlands are the most serious problems in shorebird conservation (Senner & Howe 1984). Permanently flooding estuaries (Joyes et al. 1976) and removing intertidal sand flats and mud bars (Lum 1978, Evans et al. 1979) have resulted in significant declines in wader numbers. On the other hand, islands created by dumping dredge materials can create nesting and roosting habitat for some species (Soots & Landin 1978 in Senner & Howe 1984). Unfortunately, we have already lost or altered about 60% of the mainly freshwater coastal wetlands in New South Wales since settlement (Goodrick 1970).