More than 70 species found in New South Wales before European settlement are now extinct, including 24 of the arid zone mammal species. Over 1,000 more species are listed as threatened.
Some bioregions in NSW have nearly 1,000 species of animals, including mammals, birds, reptiles and amphibians (frogs), while other bioregions may have less than 400 species. The number of species in any bioregion depends largely on the variety of places in which to live (habitats), the fertility (productivity) of those places and the mildness of the climate (particularly areas with more rainfall). Not surprisingly, the greatest biodiversity occurs along the coast from south of Jervis Bay to Tweed Heads while least biodiversity occurs in the Far West around Broken Hill and Tibooburra and in the Alpine region (the Snowy Mountains). The number of species is also adversely affected by urban, agricultural and industrial development throughout the State.
Over the past 220 years, the Australian environment has been dramatically modified by land clearing for agriculture, mining, urban development, water use and by pollution. More than 70 species found in NSW before European settlement are now extinct, including 24 of 61 arid zone mammal species (Australia has the worst extinction rate in the world for mammals). Over 1,000 more species are listed as threatened. To preserve as many species as possible a comprehensive system of reserves, linking up the remaining areas of natural habitat and waterways, is required. In addition, better management of native habitats and lessening the impact of climate change will enhance the long term survival of the State’s native species.
Distribution of Native Species
Areas of high biodiversity are found along the north-east coast and coastal ranges as well as the Gondwana Rainforests of Australia, the Greater Blue Mountains and the Lord Howe Island Group (World Heritage Areas, see map page 147). The maps show the distribution of native vertebrates in the major taxonomic groups of amphibians (frogs), birds, mammals and reptiles. As might be expected, amphibians are found in greater diversity in the eastern, moister regions of the State, while reptiles are widespread, with relatively high numbers of different species in the northern, warmer, drier areas of NSW. Bird diversity is relatively high along the coast, but occurrence of many species is dependent on rainfall, and species may be in low numbers or even absent entirely from western areas during drier periods. There are more mammal species towards the east of the State, with lower diversity in the drier western areas, particularly in the north-west.
Competition from and predation by exotic species (i.e. non-native pests) is a major threat to native animals. Many, if not most, of the animals introduced to Australia are a serious threat to biodiversity in NSW. These include European foxes, domestic cats, European rabbits, goats, feral pigs and, most recently, cane toads on the far North Coast. Higher percentages of exotic animals are found in the south-east of the State, including the South Coast, South-eastern Highlands and Alps, and the South-West Slopes.
Under NSW legislation, both individual species and populations can be listed as threatened, in four categories indicating increased risk of extinction – vulnerable, endangered, critically endangered and extinct. Threatening processes (things causing a threat, such as land clearing, water regulation, predatory animals, etc.) can also be listed. There are 288 threatened animals and animal populations listed in NSW (excluding marine mammals). Birds have the most listed species (124), followed by mammals (58) and reptiles (43). There are also frogs (28 species) and insects (16 species), and 19 threatened populations of animals. Of the 18 critically endangered species, 11 are birds and four are frogs. The highest percentage of threatened amphibians is on the mid-North Coast, while for reptiles and mammals it is in the Far West. Birds are threatened across most of the State.
Human use of the landscape involves clearing native vegetation, alteration of rivers and wetlands and building of infrastructure. This causes loss of habitat and reduced connection between patches of remaining vegetation or along rivers, which are major threats to the survival of species. Many amphibians have become regionally extinct in the past decade. This is due to modification of rivers and wetlands (including use of water in towns, industries and for irrigation), pollution and disease. One of the key threatening processes for all groups of animals is modification of their native habitat. In some areas, clearing has largely reduced native vegetation to small, fragmented areas. This has had, and continues to have, a major impact on all native species, especially mammals and woodland birds.
Department of Environment, Climate Change and Water