SYDNEY -- It is a daily death toll of staggering proportions: A million birds, a million reptiles and a million small mammals are killed every 24 hours in Australia by predators. The prime culprits are feral cats and foxes, and their unrelenting pursuit of native fauna means that Australia's mammal extinction rate is the highest in the world.
"Feral cats represent the biggest conservation issue for the country right now," Atticus Fleming, chief executive of the wildlife organization Australian Wildlife Conservancy, told the Nikkei Asian Review. "Foxes are important too, but they are more readily controlled by baiting. A fox will take dead prey. A cat doesn't -- its specialty is hunting live prey."
Australia's federal Department of Environment concurs with Fleming's view, rating feral cats as the "single biggest threat to Australia's native mammals," well ahead of foxes and habitat loss.
About 30 mammal species have been lost in the 230 years since cats and foxes were introduced to the continent by British settlers in the late 18th century. Many other small marsupials that are unique to Australia, such as the bilby, bettong, numbat, mala and quoll, have seen their numbers fall perilously low in the face of this predatory onslaught.
Feral cats in particular have thrived amid an abundance of food. In one recent case, Aboriginal rangers in South Australia found the remains of an endangered black-footed rock wallaby (a smaller version of Australia's best-known animal, the kangaroo) in the stomach of a 6.5kg feral cat.
Feral cat numbers in Australia can vary widely, with breeding rates determined by prevailing weather conditions. The latest estimates put the population at about 6 million. There are another 3 million domestic cats, some of which wreak havoc on birds, reptiles and small mammals in urban areas.
Loss of habitat and feral predation are interlinked, Fleming said. "We need to recognize that all threats interact. Land clearing makes it easier for cats to hunt."
To combat this looming environmental catastrophe, federal, state and local governments, along with AWC and other wildlife organizations such as Arid Recovery, in South Australia, are searching for practical, scientific and medical responses. The federal government has spent more than 250 million Australian dollars ($ 183 million) in the past two years devising a "threatened species strategy" and funding various projects to support it.
One solution is to build "safe houses" for native wildlife, enclosed by cat-proof fences that keep the marauders out. These steel and mesh fences, between 1.8 meters and 3 meters high with electrified wires, have a skirt at the bottom that stops foxes burrowing and a floppy top that is difficult for cats to climb. But the fences are subject to damage by large animals such as kangaroos, and are sometimes washed away by heavy rain.
One of the most important of these refuges is Scotia Wildlife Sanctuary, more than 1,000km inland from Sydney, Australia's biggest city, in a remote border area between the states of New South Wales and South Australia.
Here, in 8,000 hectares of fenced-off woodlands and sand dunes -- an area roughly equal in size to Tokyo's six central wards -- a sanctuary owned and operated by AWC is home to some of the largest remaining populations of threatened Australian native mammals, including bilbies, numbats, brush-tailed bettongs and bridled nail-tail wallabies. Scotia is the largest cat- and fox-free fenced refuge in mainland Australia.
Further north, in central Australia, AWC has embarked on an even larger project -- the creation of a feral cat-free area of 100,000 hectares at its Newhaven site, 350km northwest of Alice Springs, to house endangered mammals such as the mala, also known as the rufous hare-wallaby. Newhaven is also home to 175 bird species, including the extremely rare night parrot.
Fleming said the 9,400-hectare first stage of Newhaven is fully fenced and will be cleared of feral cats by the end of this year. A small pocket of land within the first stage is already being used for the emergency translocation of mala. Next year, AWC plans to release bilbies, burrowing bettongs and golden bandicoots at Newhaven.
The mala has important cultural significance to the Anangu indigenous people, and has already been reintroduced to the national park around Uluru, a giant monolith in central Australia that is also known as Ayers Rock.
Once Newhaven is completed it will have the world's longest cat-proof fence, running for several hundred kilometers. Australia is no stranger to big fences. It has a 3,200km rabbit-proof fence in Western Australia, and a 5,400km dingo fence running from South Australia to Queensland.
The safe haven concept has been developing in Australia for decades. Noted conservationist and 2003 Australian Environmentalist of the Year John Wamsley founded a company called Earth Sanctuaries in the 1980s to build a network of safe places for wildlife in South Australia and New South Wales. In 2002, he struck a deal to transfer four of the sanctuaries, including Scotia, to the AWC.
Along with safe havens and traditional trapping and hunting of feral cats, AWC uses indirect control methods, including managing ground cover -- which makes it harder for cats to hunt -- and conservation of native Australian wild dogs, known as dingoes, which are known to kill feral cats.
In the longer-term, science may provide a more comprehensive solution. The AWC has signed an agreement with Australia's national scientific research agency, CSIRO, to explore whether gene drive technology -- which can propagate specific genes throughout an animal population -- could help eradicate feral cats. Manipulating genes could, for example, cause females to become sterile or to have only male kittens.
"Gene drive technology is the centerpiece of our work and our best hope for the long term," Fleming said. "We already have a major research and development exercise going on at Scotia, where we have fitted GPS collars to feral cats and foxes." Data on movements is uploaded by satellite, and the information is fed into the collaboration with CSIRO.
Fleming said gene technology is already widely used in medicine. "The question is: Can we apply it to feral cats? It is a 30-year time-frame -- we have probably 10 years of research, development and testing, and then 20 years for it to work through the system."
The battle against cats is long and costly -- and not often recognized in Australian urban settings, where the animals are kept as pets and mouse-catchers. In the wild, they are deadly and patient hunters, expert at stalking and taking down prey that range from mammals to lizards, snakes and 300 million birds. Their domestic cousins kill an estimated 60 million birds a year.
Sally Box, the federal government's Threatened Species Commissioner, said recently that responsible pet ownership was part of the solution to domestic predation. Fleming put it more bluntly: "Keep your pet cat inside at all times," he said.
Fleming added: "We are winning battles. We are reversing declines, restoring populations of native animals and turning back the tide of extinction." The challenge facing Australia is to expand those successes in isolated sanctuaries to the continent's broader landscape.