Grasslands, Shrublands, Deserts
Threatened Ungulates & Predators of African Drylands: AUSTRALIA Australia has been ecologically devastated by a combination of factors over the past 200 years. A continent dominated by drylands, its great center is a vast desert. Dry shrub forest originally covered much of the rest of the country. Only in the east and the northeastern tip of Queensland did tropical or subtropical forests prevail. Its climate has become dryer over the past few centuries as a result of overgrazing by livestock and forest clearance. Deserts have grown in area, claiming an ever greater percentage of the continent. In many parts of the country, shrublands and grasslands have been replaced by desert, causing extinctions and endangering native animals. Settled by former British prisoners and immigrants, sheep and cattle ranching became the center of the Australian economy in the 19th century. Within 200 years, massive ecological destruction has resulted from their activities. Livestock were released into the delicate environment, overgrazing grasslands and other habitats. Australia is second only to China in the number of sheep grazed, some 123 million, producing wool worth $5 billion, but leaving the land devegetated (O'Neill 1997). Gordon Grigg, professor of zoology at the University of Queensland in Brisbane, estimates that 700,000 square miles of arid zone habitat, or over half of Australia, are so degraded from sheep grazing that they may become permanent desert (Grigg 2000).
Forests were cleared for grazing land, agriculture, construction of railway ties, charcoal making and fuel for factories. More than 70 percent of Australia’s native forests have been destroyed (Lines 1991). Two-thirds of all arable land has been degraded by agriculture and livestock activities; of the continent's 7,750 million square kilometers, only the remotest, unused desert areas of Western Australia have no degraded land (Lines 1991). The story of the destruction of Australia's native flora and fauna has been carefully chronicled in the book, Taming the Great South Land. A History of the Conquest of Nature in Australia, by William J. Lines (1991).
Added to the livestock and land clearing threats were a flood of non-indigenous animals released by Acclimatisation Societies to "increase Australian usefulness" (Lines 1991). Rabbits, foxes, cats, mice and rats, European birds, exotic plants and all manner of goats, camels, donkeys and horses multiplied without natural enemies. Mice, rats and rabbits reached plague proportions, consuming vegetation and crops. Cats and foxes preyed on native birds and mammals who had few defenses against them. Eurasian rats ate birds' eggs and even preyed on tiny mammals and their young.
The European Rabbit proved the most destructive introduction, proliferating into the billions. Had native mammal predators, such as hawks, eagles, Dingoes and marsupial carnivores, been protected, they might have kept the rabbits and other exotics in check. But they were driven out by hunting and habitat destruction (Kennedy 1990, Lines 1991). By 1880, rabbits had overrun vast areas of shrub, devouring leaves, branches and trunks, killing native trees and grasses (Lines 1991). In the first 8 months of 1887, 10 million rabbits were destroyed in New South Wales, but this had little effect on their numbers (Lines 1991). Fences were erected over stretches as long as 500 kilometers in Queensland, where thousands of rabbits, having stripped the land bare, piled up against the wire, starving to death in sight of the green on the other side (Lines 1991).
Australians moved into new areas, bringing the rabbits as a meat source, and by the early 20th century, rabbits had denuded most of Western Australia, including an extremely important biodiversity "hotspot" in the far southwest. Diseases and poisons, traps and hunting, all failed to eliminate rabbits, whose populations continue to rise and fall in plague proportions. In the late 20th century, experimental distribution of a poison derived from a plant to which native animals were immune was broadcast over millions of acres. This poison is known as Compound 1080 in the United States, where it was widely used against Coyotes and other predators before being restricted. It kills domestic dogs and cats as well, who die a very slow death. It also has secondary effects, i.e., animals that eat meat from animals killed by 1080, can be poisoned. It stays in the environment for long periods, killing hawks, owls and many other animals. This has brought about the protests of many humane organizations in Australia, but use of the poison continues.
Native mammals began to vanish during the 19th century, with the rate of extinction rising during the early 20th century (see Appendix). Twenty-three native Australian mammals have become extinct in the past 200 years, the majority of which are dryland species (Kennedy 1990). Australia now has the dubious honor of having experienced more mammal extinctions than any other continent (Kennedy 1990). In fact, 33 percent of arid zone mammals are extinct, and 90 percent of all medium-sized desert mammals are either extinct or threatened with extinction (Kennedy 1990). Seventy-one species of vascular plants have also become extinct (Walter and Gillett 1998). Most of the latter are dryland species. In all, 35 Australian animals have become extinct, 483 are highly threatened and 248 are in lesser categories of threat (Baillie and Groombridge 1996). Of 15,638 native vascular plants, 2,245 species are threatened, a rate of 14.4 percent (Walter and Gillett 1998).
Australia's land mass is approximately the same size as the lower 48 U.S. states, but it has proportionately far more threatened species. Endemic marsupials, such as many types of wallabies and native rodents other than large kangaroos, have either disappeared altogether from territories that once covered thousands of square miles or cling to existence in tiny reserves on small islands off the coasts where non-native animals are absent. With such limited ranges, many will probably die out. In fact, the majority of once wide-ranging species have been squeezed into small areas, a fraction of their original ranges. A wave of extinctions among species that are now endangered will probably occur within the next 50 years, according to some scientists. The majority of Australia's threatened species exist outside national parks and nature reserves, which contributes to a pessimistic view of their long-term survival.
The wildlife that inhabited Australia prior to European settlement included the most diverse marsupial fauna in the world. The majority inhabited dryland regions and have strange-sounding names that reflect their total uniqueness, resembling no other mammals on Earth. Quolls, wallabies, wombats, koalas, pademelons, potoroos, and bettongs are among these fascinating creatures. Almost all are now either extinct or in various states of endangerment. Each evolved over hundreds of thousands or millions of years to occupy an individual ecological niche, adapting to a variety of arid environments.
One of the rarest and strangest is the Bilby, or Rabbit-eared Bandicoot (Macrotis lagotis). A small burrowing animal, it has large ears, a long, pointed snout, and soft blue-grey fur washed with pinkish-brown, ending in a black-and-white crested tail, carried like a stiff banner while it canters along (Strahan 1995). The Bilby male can reach over 21 inches, while the female is only 11 inches long (Nowak 1999). Their burrow, which they can dig very rapidly with their clawed front feet, is spiral and up to 6 feet deep and 10 feet long, affording them protection from the searing heat of their desert habitat (Berra 1998). Sheltering during the day in their burrow, they do not lie down to sleep, but squat on their hind legs and tuck their muzzle between their forelegs with their long ears folded forward over the eyes (Nowak 1999). At night, they emerge to feed on insects, small vertebrates, seeds and fungi. Able to survive in the driest and hottest of Australian deserts, Bilbies once occupied all of central, western and southern Australia (Kennedy 1990). Their preferred habitat of hummock grasslands and acacia shrublands with spinifex and tussock grass has been degraded by cattle and rabbits (Kennedy 1990), and they have been trapped and preyed on by cats and foxes (Strahan 1998, Nowak 1999). Close to extinction, Bilbies survive only in a few isolated colonies in Western Australia, the Northern Territory and southwestern Queensland (Nowak 1999). The species is listed as endangered by the U.S. Endangered Species Act and Vulnerable by IUCN. Captive-breeding programs have been successful, and reintroduction programs are attempting to bring the species back to portions of its former range (Kennedy 1990).
A similar species, the Lesser Bilby (Macrotis leucura), inhabited the deserts of South Australia and Northern Territory until the early 20th century when it became extinct. Last seen in 1931, this delicate marsupial was eliminated by the same factors that have endangered the Bilby (Nowak 1999).
The Eastern Barred Bandicoot (Perameles gunnii), a close relative of Bilbies, inhabits heath, grassland and dunes in southern Victoria and Tasmania. With smaller ears than the Bilby, it also has soft, grey fur, but its back is barred with horizontal stripes of white. It has nearly disappeared from mainland Australia in the southeast and remains only in Hamilton in southwest Victoria, surviving in suburban gardens, nearby grasslands and a car dump site; three new captive colonies have been established elsewhere in Victoria (Kennedy 1990, Strahan 1998). Foxes and other introduced predators, as well as habitat destruction, are blamed for its perilous status. In Tasmania, where foxes are absent, it is more widely distributed, but it is declining here, too (Nowak 1999, Strahan 1998). Total population was estimated at only 633 in 1985, declining to 236 in 1988 and less than 100 in 1992 (Nowak 1999). Its counterpart, the Western Barred Bandicoot (Perameles bougainville), once ranged from central New South Wales west to the Indian Ocean. Today, this species' entire habitat consists of two small, predator-free islands--Bernier and Dorre Islands--off the central coast of Western Australia (Kennedy 1990). Native to a semi-arid habitat of shrub and open plains, its decline to near-extinction went unchronicled but is assumed to have been caused by habitat destruction, competition for food with rabbits and predation by foxes, cats and domestic dogs (Nowak 1999).
Two other members of the genus are now extinct: the Desert Bandicoot, Perameles eremiana of southern Northern Territory, northern South Australia and southeastern Western Australia, was last seen in 1931; a close relative, Perameles fasciata, disappeared about 1867. Yet another species, the Pig-footed Bandicoot (Chaeropus ecaudatus), the sole member of its genus but very closely related to the species above, became extinct in 1907 (see Extinct Species List in Appendix). Such devastation of entire groups of endemic species, mirrored in the fate of many other native Australian marsupials, has no parallel in recent history.
Another extraordinary family of marsupials is in steep decline. Wombats are heavy, up to 5 feet long, with thick bodies, very short legs, and tiny eyes; they weigh up to 77 pounds (Nowak 1991). In spite of their ungainly appearance, they are able to achieve speeds as high as 40 miles per hour for short distances (Nowak 1999). Endemic to Australia, there are three species in the Vombatidae family. Prior to European settlement, they were found throughout the continent in open grasslands and savannah with scattered trees and woodlands. Quite timid, they spend most of their time during the day, especially in hot climates, in extensive burrows which they excavate with their long, sharp claws, venturing out at night to feed on grasses, roots, bark and fungi (Nowak 1999). Their complex of tunnels leads to underground chambers so intricate that they are called cities. Sometimes several wombats occupy them, encountering one another only during breeding season, yet there is only one entrance.
All wombats have suffered declines from persecution by farmers who fear cattle will become injured by falling into the burrows, and many have been accidentally poisoned and gassed in rabbit-control programs because the latter animals seek shelter in wombat burrows (Nowak 1999). Ranchers routinely fill wombat holes (O'Neill 1997). Destruction of grasslands from overgrazing and agriculture has also eliminated populations (Kennedy 1990).
In spite of their somewhat imposing appearance, wombats are extremely gentle and playful in captivity (Nowak 1999). During a rash of forest fires in 1993 in New South Wales, many Common Wombats (Vombatus ursinus) became burned when they left their burrows to forage. Their paws were scorched by hot, smoldering soils, and they were unable to move; local people rescued many of the burned and frightened animals and nursed them back to health in their homes. Even though traumatized and shy of people, wild wombats could be carried about like huge puppies, submitting docilely to veterinary treatments.
Two of the three wombat species are listed in Australia's Endangered Species (Kennedy 1990). The most endangered is the Northern Hairy-nosed Wombat (Lasiorhinus krefftii), which is on the brink of extinction. Gone from New South Wales and southeastern Queensland, this wombat is confined to a tiny area of 15.5 square kilometers in Epping Forest National Park, east-central Queensland (Kennedy 1990, Nowak 1999). Once native to open savannah and eucalypt woodland in New South Wales and Queensland, this species' total population has been reduced to only about 70 individuals (Nowak 1999). This wombat has been classified as Critical by the 1996 IUCN Red List (Baillie and Groombridge 1996). These wombats are being studied by biologist Andrew Woolnough.
The Southern Hairy-nosed Wombat (Lasiorhinus latifrons) has declined in numbers and distribution from its original wide range from southeastern Western Australia to New South Wales, the entire southern half of the continent. Still fairly common in some areas, this species occupies a more arid habitat of near-desert conditions and has declined because of land clearance, overgrazing, and persecution by farmers, many of whom shoot this animal on sight (Kennedy 1990) based on mistaken beliefs that wombats damage fences and compete with livestock for grazing (Nowak 1999).
Australian grasslands have been severely degraded by livestock grazing. Once covered in perennial grasses that formed erosion-resistant mats, what vegetation remains is dominated by annual grasses (Fitzherbert and Baker-Gabb 1988). During the 19th century, untold millions of sheep and cattle grazed Australia's grasslands and deserts, and the damage they did to the soil and vegetation may be irreparable. Native saltbush has been eliminated on some steppe lands, and the diversity of native plants has been greatly reduced. Only since the 1940s have large private ranch holdings been broken up, and Australian ranchers have developed a greater awareness of the negative effects of livestock on the land (Fitzherbert and Baker-Gabb 1988).
Sheep ranchers have nearly eliminated many native animals by constructing a 3,307-mile fence across southeastern Australia to prevent Dingoes from entering southern areas where sheep are raised (O'Neill 1997). This fence prevents natural migrations of kangaroos and Emus, who can be seen running along the fence for miles, seeking an opening to cross (O'Neill 1997). Many die in collisions with the fence or from dehydration after trying for days to enter an area with grazing and water. The fence has not succeeded in keeping Dingoes, which number about 1 million in the country, out of sheep territory (O'Neill 1997). Dingoes are savagely persecuted in sheep country, poisoned, trapped in steel jaw leghold traps, shot and hung from fence posts (O'Neill 1997).
Australia's birds have also suffered from desertification and other activities of European immigrants. Ten Australian parrot species are listed in various degrees of threat by BirdLife International, and one is now considered extinct (Collar et al. 1994). The Paradise Parrot (Psephotus pulcherrimus) was last seen in 1927 (Greenway 1967). This beautiful parrot of central eastern Australia's grasslands was probably never very common; it lived in grassy woodlands and river valleys, the very habitat that was usurped by cattle ranchers (Fitzherbert and Baker-Gabb 1988). These were technicolor birds. The male was a dazzling combination of turquoise and emerald green on his breast, cheek and flank feathers, set off by black on wings, head and tail; he had large splashes of red on his wings, belly and forehead and his dark eyes were encircled by yellow. The female was a slightly paler version of the male. Their habitat degraded in the 19th century with heavy livestock grazing, and by 1915, these birds had become very rare (Forshaw 1989). Great beauty and relatively small size--11 inches in length including the tail-- made it attractive as a cage bird. Paradise Parrots were tame, feeding in pairs on the ground, and so were easily trapped for the cage bird trade, which pushed the already rare birds to extinction.
The rarest grassland parrot is the 9-inch Night Parrot (Geopsittacus occidentalis), whose greenish-yellow plumage mottled with dark brown, black and yellow allows it to blend into its spinifex grassland habitat (Forshaw 1989). This extremely mysterious species, seen in widely scattered localities of the arid interior of Australia, disappeared about 1912 and was thought extinct; then the species was sighted in 1979 in South Australia when several Night Parrots were flushed from underneath bushes (Forshaw 1989). These parrots spend most of their time on the ground and are thought to be nomadic. More recently, they have been seen in Western Australia, and a dead Night Parrot was found in 1990 (Collar et al. 1994). Grazing by livestock and the threat from introduced predators, such as foxes and cats, have contributed to their decline (Collar et al. 1994). They are so rare that no studies have been carried out on their diet or life history, but it is presumed to be nocturnal.
The greatest threat to Australia's grassland plants, preventing many of them from germinating, is heavy grazing by sheep, cattle, rabbits, goats, horses and donkeys (Kennedy 1990). One outspoken conservationist and landowner, John Wamsley, has established a sanctuary for native wildlife and plants. He excludes all livestock, foxes, rabbits, cats and other exotics with strong fences. He claims that the Australian government lacks resolve in protecting endangered species and their habitats, and with more fences and sanctuaries similar to his own, he believes that native wildlife could reoccupy habitats and recover their numbers. He has enlarged his preserve to over 100,000 acres. This may be the only area in mainland Australia where native mammals are increasing.