Australia and Southeast Asia

Australia and Southeast Asia — page 3
The Wallace Line Australia and the islands of New Guinea Sulawesi Halmahera and Flores are separated from the islands of Borneo Bali Java Sumatra and the mainland of Southeast Asia by an invisible line the Wallace Line This is named for the British naturalist Alfred Russel Wallace who recognized that the mix of animals one side of it were very different from those on the other side This is especially true for mammals and birds For example the native mammals of Australia and New Guinea are marsupials those to the northwest of the line are not During ice ages when ice sheets expanded at high latitudes the sea level fell and the islands to the northwest of the Wallace Line became joined in one landmass as did those to the southeast Even then however a trench of deep ocean still separated the two areas of land as it had for more than 50 million years That separation had allowed species to evolve separately and differently on either side Above the tree line in the Great Dividing Range of Victoria and New South Wales is high-altitude alpine grassland Here conditions are mild for much of the year but there is snow cover in winter The Critically Endangered marsupial Mountain Pygmy-possum lives near Mount Bogong and Mount Higginbotham Semiarid grassland and desert stretch across Australia’s vast interior Much of the natural grassland has been turned over to arable farming or the grazing of animals Some native animals have suffered as a result of these changes for example the plains wanderer a ground-living bird now classified as Endangered Areas of suitable habitat low plants with plentiful bare patches are just a small fraction of what they once were In good years plains wanderer numbers may reach 7,000 but in years of harsh drought they may fall to only 2,000 Another Endangered bird of this environment is the night parrot whose nocturnal lifestyle makes it very difficult to estimate its population The Australian interior or Outback can experience scorching daytime temperatures and long periods without rain although when it falls the rain may be torrential Despite these challenging conditions this environment supports large numbers of animals Many remain in underground burrows during the day only becoming active at night This is the domain of many reptile species including bearded dragons perenties and thorny devils which have grooves in their body scales to channel dew to their mouth 6 The Great Barrier Reef lies off the northeast coast of Australia and is the largest coral reef on Earth stretching 1,600 miles 2,575 km The reef’s biodiversity is extraordinary including more than 1,500 species of fish 17 species of sea snake 30 different kinds of dolphin and whale and a healthy population of dugongs It is protected by law but as with all reefs is likely to suffer as global ocean temperatures rise as a result of climate change New Zealand The two main islands of New Zealand North Island and South Island have big areas of temperate forest and high-altitude meadows on mountains such as the Kaikoura Ranges New Zealand’s only native mammals are three species of bat but one of the biggest threats to the country’s fauna has come from introduced mammals rats cats and dogs especially since many native birds are flightless This threat explains why so many native animals now live only on rocky offshore islands These natives include the tuatara a reptile in a family of its own and the Critically Endangered kakapo a nocturnal flightless parrot that is adept at climbing trees Several hundred miles southeast of New Zealand the small Chatham Islands are home to many seabirds including Chatham Islands taiko and Chatham petrel which breed nowhere else A termite nest in Kakadu National Park Australia Several endangered mammals birds and reptiles live in this preserve