By Tracy Sorensen
Nearly half of Australia's marsupials are in danger of extinction unless action is taken now. According to a new report released by the World Wide Fund for Nature, 27 species are endangered or vulnerable, with a further 33 animals in a "potentially vulnerable" category. Taken together, these species account for 49% of the continent's marsupial species.
In just over 200 years of European settlement, Australia has notched up the world's worst record in mammal extinction: this country accounts for about half the world's mammals that have become extinct in modern times.
Of the marsupials present 200 years ago, 10 (or 7% of the total) are known to have vanished. Others may have disappeared before their existence was recorded.
The urgency of the situation is illustrated by the plight of the mala, or rufous hare-wallaby. Between the first draft of the report and its launch on August 10, the last wild population was wiped out by fire and predation by introduced foxes. Once occupying 25% of continental Australia, the mala is now confined to nature reserves on Bernier and Dorre Islands off the Western Australian coast.
The northern hairy-nosed wombat is probably worse off: habitat destruction and grazing competition with cattle, sheep and rabbits have reduced the species to just 65 individuals in central Queensland.
WWF senior project officer Michael Kennedy told Green Left in an interview on August 14 that the preservation of endangered species is crucial to this country's obligations under the
biodiversity convention signed at the Earth Summit in Rio.
Australia is one of the 12 countries in the world considered "mega diverse" — countries which, between them, contain 60-70% of the world's species, and a large number of unique species. Australia is the only economically developed country among these and could, therefore, play a leading role in the preservation of the earth's biodiversity.
But for the moment, back at home, the fight to preserve endangered wildlife is still being waged — literally — "on the ground".
With patchy state and federal legislation and policy, and a debate in the mainstream media which still pits the long-footed potoroo against paying off the mortgage, skirmishes continue between developers and environmentalists over this or that bit of remnant habitat.
Some of these "punch-ups" could be avoided, says Kennedy, if the movement to save endangered species could secure adequate legislation and money for recovery and preservation programs.
It is a campaign which appeals to both hearts and minds: the emotional appeal of "cute" endangered animals can, says Kennedy, be a "way in" to broader educational campaigns about the principles of biodiversity.
The WWF report, Australasian Marsupials and Monotremes: An Action Plan for their Conservation, was developed over three years by members of the Australasian Marsupial and Monotreme Specialist Group, a subgroup of the International Union for the Conservation of Nature, and compiled by Kennedy.
(Marsupials are pouched mammals. Monotremes are egg-laying mammals. Australia's two monotremes are
the platypus and the echidna, neither of which is endangered.)
The plan provides a detailed guide to the 27 endangered and vulnerable species, indicating the conservation agency responsible, and estimating the cost of each species' recovery program. The plan estimates that all up, the program will cost $24 million over 10 years, about $90,000 per species per year.
"That average price tag will increase significantly unless we begin the process immediately", says Kennedy.
What are the main threats to marsupials? While habitat destruction (logging, clear-felling for agriculture and urban settlement) has caused local extinction, the report notes that it was the interaction of three other (but related) factors which finished off the 10 marsupials known to have been lost.
These factors are changes to habitat caused by introduced herbivores, homogenisation of habitat following changed fire regimes and the spread of exotic predators.
- The introduced herbivores include rabbits, goats, cattle, sheep, donkeys, pigs and camels, which now range widely over the continent, competing with native animals for food and altering vegetation patterns and habitats. Competition for access to drought refuges — areas remaining rich in nutrients through dry spells — can be particularly devastating for native animals.
- Fire regimes have changed since European settlement, from small fires lit throughout the year, to infrequent, large, summer fires that wipe out much of the variety of vegetation. The report notes that the disappearance of mammals from the deserts of Western Australia, north-western South Australia and south-western
Northern Territory coincided with the decline of Aboriginal population and the subsequent change in fire regime.
- Australian marsupials evolved for millennia without having to contend with a fox-sized predator. Today, marsupials are delicacies for the fox and feral cat.
The mammals most affected since European settlement have been the non-flying, medium-sized animals weighing between 35 grams and 5500 grams — the "critical weight range". Eight of the 10 extinct marsupials were in this range; of the 27 endangered or vulnerable marsupials, all but two lie in the critical weight range.
The greatest concentration of endangered and vulnerable marsupials — 16 species — is in the south-west of Western Australia and Shark Bay. Queensland, with 10 threatened marsupials, has the second highest concentration.
The WWF's action plan outlines a crisis management program for the "top 27" (including measures such as captive breeding programs and reintroduction to areas where animals are locally extinct), while urging recognition of the fact that the "potentially vulnerable" will move into the vulnerable category unless coordinated long-term management programs backed up by legislation are introduced now.
The necessary legislation would apply to both private and public land with "no exemptions".
"We are trying to answer industry's cries for clear national guidelines, but you give them that and they still scream blue murder. You can't win. The legislation has to be strong enough to ensure that if you find a threatened species, you stop until it has been sorted out."
This would not stop all development in its tracks, said Kennedy. Strong wildlife protection laws in the United States, for example, brought a great deal of consultation, but only a tiny proportion of projects were halted.
"Governments are not now obliged to recover species which are threatened. They are protected, which means that you can't shoot, kill or step on them, but that doesn't mean you have to protect their habitats."
Threatened species legislation has been introduced, or is being drafted, in most states and in federal parliament. A far-reaching private member's bill has been introduced by Democrat Senator John Coulter, which, unlike Labor's proposed legislation, is not just restricted to activities on crown lands (1% of the continent!).
An example of legislation going in the wrong direction is that proposed by the NSW Liberal/National Party coalition.
"Their legislation would only recognise species agreed to be endangered at a national level. The most famous wallaby in this state, the yellow-footed rock wallaby, is endangered here. There are 200 left way out west near the borders of the three states. It's not endangered in Queensland or South Australia. At a national level, it fits the third category, potentially vulnerable.
"Under the coalition's proposal, the wallaby wouldn't get a look in in this state. You can imagine what would happen if every state took that view. The biodiversity that exists in these borders is ours to maintain. Whatever lives here, breeds here or just overnights here demands protection.
"You can't say: 'We've got four isolated populations left, we can knock off three and keep one'. That's biological nonsense. You have to conserve diversity. Genes may differ from one
population to the next. The aim is to conserve ecosystems in their variety, species in their variety, and genes in their variety."
Dr Roger Martin, research associate of the Department of Ecology and Evolutionary Biology at Monash University, told Green Left that preserving more than just a representative population could be likened to an "insurance policy".
"If you have a population surviving in isolation, particularly if it is a small population, it is very vulnerable to chance events, be it disease, be it bushfire, be it drought. If you are investing everything in one remnant population, any chance event can wipe it out.
"You are really covering your potential losses by having a lot of small populations rather than one small population."
Preserving biodiversity, say scientists, is actually about preserving adaptability. Adaptations are based on the selection of "useful" genetic variations (or mutations) between individuals in a species. The process is clearly illustrated by the koala.
"Koalas extend from north Queensland, right around the south-eastern coast down to Kangaroo Island in South Australia. As you go from one extreme to the other, as you go from the cool, temperate regions up to the hot tropical regions, your koalas change."
In the south, the average adult male weighs about 13 kilos. In the northern regions they weigh about seven kilos and have much shorter fur — adaptations to suit the climate.
"Populations that are unable to respond to change go extinct", write Graeme George and Peter Brown of Deakin University in the
WWF-sponsored report. Accumulated genetic variability "needs to be preserved if a threatened species is to be conserved with some long-term evolutionary potential".
They explain that there are two components to genetic variability: variability across a species, and variability within an individual. The "fittest" individuals and species are those with the most variability.
Under "normal" conditions, a certain level of variability across the species is lost through a process called "genetic drift", or the randomness of inheritance. In a large breeding population, this loss is compensated, over time, by input from individuals outside the "home territory" of a group of animals.
Small populations don't benefit from this compensatory factor: they are more likely to feel the effects of genetic drift, and, as a result, lose the resilience necessary to cope with environmental challenges.
"With the loss of each isolate [isolated population]", write George and Brown, "the gene pool of the species is diminished, and each loss becomes a step toward the species' extinction".
Species preservation therefore rests on the preservation of as much genetic variation as possible. George and Brown recommend genetic management which includes increasing total population size; providing greater geographic spread in case of catastrophe; and exposing the gene pool to a greater range of selection pressures.
This management of endangered animals was needed "in addition to the more traditional environmentally oriented conservation measures — habitat protection and restoration, control
of predators, legal protection, etc".
The need for thorough research is obvious. The March 1992 National Environment Report, a newsletter produced by the Democrats, recounts an attempt at reintroduction that went badly wrong.
After 17 years of careful planning, selective breeding and intensive scientific studies, parma wallabies were returned to mainland Australia from a population found on an island off New Zealand.
Forty-seven of the tiny marsupials were let out in an inaccessible gully in the Illawarra catchment area of NSW. Within eight weeks, every one of them was dead: snapped up by foxes.
"For six months ... poison baits [had been laid] and the fox problem had been dramatically reduced. But for the foxes that were left, the parma were such a delicacy that they completely ignored the baits until every wallaby had been stalked and killed."
While millions of dollars have been spent on researching the problems of marsupials — particularly diseases of koalas — Dr Roger Martin suggests that the money could now be better directed.
"We know a lot about the biology of koalas ... there's probably not too many marsupials that we know more about, in both the general ecological situation and in the very detailed biology." Other marsupials, like the northern hairy nosed wombat, could do with some research money.
"I think overall the status of knowledge [about koalas] is good, except for some exceptional cases, such as the remnant koala population of the south-
east. We know the problem. The problem is habitat loss. I think we have just got to tackle the tough politics of trying to reverse the trend in habitat loss."
Tough politics, or what Michael Kennedy calls a "punch-up" is being played out over the NSW south-east forests right now. In July, about 200 activists converged in the forest near Eden to try to save from logging the old-growth trees and the habitat they provide for koalas, yellow-bellied gliders and southern brown bandicoots.
"Because of the very nature of our progress, all wildlife is threatened", says Kennedy. "Unless we get some good policies and programs, then in the first part of next century there'll be a second wave of extinctions.
"The causes of the extinctions of the last 200 years are still there. Cattle and sheep, rabbits, foxes, feral cats, habitat pollution and destruction: all those things that caused the demise of species are still there.
"Marsupial decline started in the arid zones. Now it is moving south, east and west, so those forces are going to take hold of the temperate zones in the next 20 years and give them a good shake.
"We haven't seen extinctions on the east coast yet, in the forests, but we've seen decline and we've seen fragmentation. Once they get to a certain level, they can't cope, and there's an almighty crash, and that's going to happen to those species soon.
"So you've got to move now. That means taking account not just of the species themselves but of the systems that they are a part of, making sure their processes are still connected and working, still producing new genes, new species, to ensure that evolution continues."