Current and Historical Occurrence of Platypuses, Ornithorhynchus anatinus, around Sydney.

Abstract

No formal survey of platypus (Ornithorhynchus anatinus) distribution around the greater Sydney area has previously been carried out. However, using 126 records of 0. anatinus from various sources (Pre-1900 (7), 1900-69 (43), 1970-89 (57), 1990-96 (19)), an assessment of the current and historical occurrence of the species in this area has been made. The species has been observed regularly since European settlement in the upper reaches of the Nepean River and its tributaries above the sites of the current Sydney water storages. Apparently once common in the Nepean River between the current water storages and the Warragamba River junction, the species is now seldom observed in this section of the river. It was previously more common in the lower reaches of the Nepean and upper Hawkesbury Rivers and platypuses are still occasionally recorded in this part of the river system. The species also still occurs upstream of the Lake Yarrunga storage in the Kangaroo River. It is currently found in streams of the Lake Illawarra catchment and the south coast, as far south as Berry, and in the Wollondilly and Coxs Rivers upstream of Lake Burragorang. Platypuses are no longer reported from the streams flowing through the Wollongong metropolitan area. Some recent records exist for the Sydney metropolitan area, but most are from national parks. The river systems around Sydney, Wollongong and their satellite settlements have been severely degraded by a range of human activities since early European settlement. At present it is not possible to attribute changes in 0. anatinus distribution to any single human activity over that period.