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An introduced species to Australia, the Asian Water Buffalo, thrives due to the absence of its natural predator, the Tiger.
Photo: Chris Johnson

September 11, 2001
Threats to Native Biodiversity
  Real Audio

Log Transcript

Since the beginning of the voyage, the Odyssey crew have born frustrated witness to the devastation brought about by the introduction of non-native species into countries from the Galapagos Islands to Papua New Guinea. Nowhere has the problem been as severe as it is in Australia.

Australia has the worst record in the world for the loss of native animals, in particular its mammal species. The small to medium sized mammals in the arid zone have not faired well since the arrival of Europeans. Over the past two centuries at least seventeen species have been lost, more than in any other continent over this same period. Many others are threatened with extinction or only survive on offshore islands. Several factors have been responsible for this remarkable rate of native species loss including the clearing of land for agriculture and urban development, as well as introduced species that prey on them. Cats and foxes compete with them for food while cattle, sheep, buffalo and pigs compete for habitat.

As many native animals become rarer and inch closer to extinction, several introduced and pest species continue to thrive. Excessive grazing pressure by introduced hard hoofed animals is causing severe land degradation here in the Northern Territory through the loss of vegetation and subsequent soil erosion. Almost seventy-five percent of Australia is rangeland, most of which is found in the arid interior and to the north. Farmers control the majority of this land, which has caused the rich assemblage of native flora and fauna to become extinct or severely reduced to small isolated pockets. The adoption of European management practices, which are unsuitable for this fragile environment, has caused natural pastures to be severely destabilized.

Unfortunately, introduced species are not only restricted to farmland. In the Northern Territory, feral pigs numbering in the millions, threaten World Heritage areas. Pigs are omnivores that graze, root and scavenge food including grass, frogs, and invertebrates. Their habit of digging and wallowing also destroys the fragile nesting sights of crocodiles, turtles and ground birds. In addition, they carry several diseases and parasites.

The 'Feral Pig' wallows, digs and grazes around the fringe of billabongs scavenging for food including the eggs of crocodiles, turtles and nesting birds.
Photo: Chris Johnson

Water buffalo are another problem species, brought from Asia to Northern Australia. They have also adapted well to the 'top end'. Their semi-aquatic habits, heavy weight and hard cloven hoofs, cause extensive environmental damage including crushing nesting sights, silting waterways, eroding precious top soil and promoting weed invasion.

The control of these animals is difficult due to the dense vegetation of national parks and World Heritage areas such as Kakadu, in which they are found, combined with rapid growing populations due to a lack of natural predators. Densities are often greatest on sensitive floodplains and wetlands adjoining forests. Furthermore, there is a likelihood that methods of control such as the use of dogs, shooting or poisoning will adversely effect wetlands and native animals. In response to this growing problem, key interest groups are cooperating in an effort to control the damage by live trapping of these animals, in the hope that meat exports may transform these pest species into a valuable economic resource.

This is Genevieve Johnson speaking to you from the Northern Territory.

Log by Genevieve Johnson

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