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WARNING BELLS first rang in 1985. That was when Steven Brown, a vet
at the University of Queensland, in Brisbane, and his colleague Frank Carrick
announced that an epidemic of chlamydia was sweeping through Australia’s
koala population, leaving animals blind, sterile or dead.

Could this mean that the country’s most famous marsupial, its ‘animal
ambassador’, was on the slippery slope to extinction? The controversy surrounding
this question continues to this day. Ian Hume, professor of biology at the
University of Sydney, is in the middle of the dispute. ‘There are those
who think that they are on the verge of extinction, that the disease chlamydia
is going to wipe out the remnants of the population. There are those of
us with a more moderate viewpoint that as long as we look out for the habitat
of the animals, we should be OK. If we don’t, then we’re going to be looking
at very, very small numbers in the future. And there are those at the other
end of the spectrum, where everything’s hunky-dory.’

One of the main reasons why the experts do not agree is that there remains
a startling degree of dissension over the fundamental facts of koala life.
Many researchers think that no one knows enough about the biology and ecology
of the species to say whether the koala is about to become extinct. Yet
others, such as Roger Martin, of Monash University in Melbourne, argue that
there is more than enough information both to answer this question and to
develop effective strategies for managing the koalas to ensure that they
survive.

Without agreement on the basics, it is difficult to define the problem.
For instance, if Brown and Carrick are right and koalas are seriously endangered,
their numbers must be falling. If they are, will the population dwindle
to nothing in 20, 30 or 40 years? There is no consensus on this. There is
not even agreement on the number of animals still living outside the country’s
game parks and zoos. The figure commonly offered by Brown and others is
400 000. But Martin claims there is ‘absolutely no basis for that estimate’
because there have been no systematic surveys of koalas. He thinks that
in the state of Victoria, the problem is not too few koalas, but too many.
A growing population is eating itself out of house and home, creating a
‘management’ problem for wildlife biologists working to preserve healthy
koala colonies.

It is difficult even to assess how many koalas there were in the past.
Were there cycles or patterns in the population that could help to explain
what is happening today? Here, scientists are limited more by a shortage
of information than by conflicting data. Early European records and aboriginal
myths indicate that the slow- moving creatures were a prime target for native
hunters. Fires and drought also kept their numbers in check. Later, as European
settlers shot hundreds of thousands of koalas and shipped their furs to
Europe and North America, the animals began to disappear from some areas.

But scientists can only guess what the overall koala population was
before Europeans settled Australia, or even after hunting was banned in
1927. According to Alistair Melzer, an ecologist at the University of Queensland,
in the last year koalas were legally hunted, approximately 600 000 skins
were exported. This figure, along with other anecdotal evidence, indicates
that populations were much larger before the European settlers arrived.
Today’s koalas, he feels, are in sharp decline.

To settle the question of how many koalas are left in Australia, delegates
to a ‘koala summit’ in Sydney in late 1988, urged the government of New
South Wales to fund studies of the numbers and distribution of koalas. The
assembled experts also called for more work on those aspects of koala biology
which make it so well adapted to its highly specialised environment. The
recommendations that emerged from the conference highlight areas of certainty
and uncertainty that underlie the discussion about the demise of the koala.
For example,there is no doubt that koalas rely almost exclusively on eucalyptus
trees for food, water and shelter, that they browse regularly on only half
a dozen of the 500 or so species of eucalyptus, and that they prefer the
leaves of particular trees. ‘But what is it about those trees that makes
them attractive?’ asks Melzer. ‘You can have two trees standing side by
side, both of them the same species, and one the koalas will eat and one
they will never eat. What the difference is between those trees, we simply
don’t know.’

Similarly, the fastidious koala will sift through 9 kilograms of leaves
a day for the half kilo it eventually eats. But biologists cannot agree
on what makes some leaves more desirable than others. Gordon Sanson, of
Monash University, reckons that koalas prefer tender young shoots. His colleague,
botanist Neil Hallam, believes that the animal chooses leaves for other
reasons, such as texture, thickness and composition. ‘The animals don’t
just nibble away at the choicest and greenest tips,’ he says.

It is not that some researchers are wrong. The number of koalas and
their way of life seems to vary widely from state to state and colony to
colony. So generalising from different types of studies of different populations
can be tricky. Not enough solid data are available on koala biology, ecology,
and behaviour to be certain what threatens particular koalas and to what
extent.

While the biologists continue to argue about details, they do agree
that Australia’s koalas face three great threats: disease, destruction of
their habitat and predation. According to John Woolcock, a veterinary microbiologist
at the University of Queensland, the organism infecting both wild and captive
koalas is similar to the human pathogen that causes psittacosis, or ‘bird
lover’s disease’. At least two strains of psittaci are causing ‘koala chlamydia’,
one transmitted sexually and the other through contact with contaminated
body secretions which infected koalas leave on trees and leaves. The disease
affects the eyes and the urinary and reproductive tracts of its victims.
‘It brings tears to the eyes’ to see blind animals or those with weeping,
inflamed eyes, says Woolcock. The less obvious infections of the urinary
tract can lead to kidney damage, and infection of the reproductive tract
can make koalas sterile. Some animals eventually die.

It is difficult to know how many animals are infected with chlamydia.
Outside parks and zoos koalas blend into the forest and are hard to spot.
Only the more advanced cases of infection can be diagnosed on sight. Studies
of captive animals and sick or dead koalas brought into parks and research
centres suggest that the organism is widespread. Nonetheless, many scientists
doubt that the disease will push the species to extinction.

Martin and Anthony Lee, another zoologist from Monash, pointed out in
their book, The Koala: a Natural History, that the disease is endemic to
koalas. They have lived with it for many thousands of years. Yet a proportion
of infected animals continue to breed and, at least within Victoria, few
animals show symptoms they would regard as debilitating. ‘From these and
other observations we have concluded that chlamydiosis may not pose a threat
to the animal,’ they write.

As a vet, Woolcock finds the effects of chlamydia on individual animals
extremely distressing. But not all infected animals develop serious complications;
chlamydia appears to affect similar populations in very different ways.
Many interacting factors, including overcrowding and poor nutrition, may
account for this. But the exact relationship between those variables must
be teased out before the magnitude of the problem can be determined and
solutions found, believes Woolcock. Hume agrees. Chlamydial disease is the
result of all the problems koalas face, not the cause of those difficulties.
Hume, along with a rapidly growing number of biologists and ecologists,
feels that the greatest menace is destruction of the koala’s habitat.

Around 80 per cent of the eucalyptus habitat has disappeared in the
past two centuries and much of the remaining habitat has been disturbed.
Removal of just one or two species of eucalyptus from a forest may force
resident koalas to travel farther afield for acceptable fodder, expending
more of their naturally low reserves of energy. If hungry koalas cannot
forage normally across their range, they will strip all the leaves from
the available trees, eventually killing them. The koalas then starve.

As Australia’s eucalyptus forests give way to farming, logging, grazing
and urban expansion, koalas retreat into increasingly marginal countryside.
They may also be thrown into the company of humans, an association that
is rarely good for them. Ron Brown, an architect and town planner at the
University of Queensland, says that because most city officials are unaware
that koalas often live on the outskirts of Australia’s eastern towns and
cities, they seldom consider setting aside protected zones to safeguard
the koalas. People move into prime koala habitat, bringing with them all
the paraphernalia of modern living. For instance, koalas drown in backyard
swimming pools, and the commonest cause of death is ‘Dunlop disease’, being
struck by a car or a truck. The phenomenon is so common, scientists regularly
collect road casualties for their research.

While some forms of human ‘predation’ have begun to disappear – many
hunters now avoid taking pot shots at koalas, and farmers are increasingly
protective of koalas on their land – pet dogs are a growing menace. This
is especially true in fragmented habitats where the animals have to cross
open ground to reach new supplies of food. ‘A koala can hold its own fairly
well against one dog,’ says Brown. ‘But against two or more dogs, the koala
just doesn’t stand a chance.’

Everyone agrees that the stresses koalas face should be kept to a minimum.
No one disputes that good koala habitat must be preserved if koalas are
to survive in the 21st century, but no one can agree on what makes an ideal
koala habitat.

Organisations such as the Australian Koala Foundation have capitalised
on public concern about the plight of the koala to raise funds for research.
In the past three years, the Foundation has given A$300 000 (about Pounds
sterling 150 000) to various researchers and institutions through Australia
to study koalas.

Not all investigators are comfortable with the newfound role of koalas
as scientific fundraisers. Sanson feels that preservation groups have exaggerated
the threat of extinction. ‘Koalas will not become extinct in 40 years, as
some people claim. That is nonsense used to gain sympathy and funds for
further research,’ he says. ‘I tend to think that some of it is verging
on the dishonest.’ Others quietly express concern about a potential ‘backlash’
if donors feel they have been misled.

¿ìè¶ÌÊÓƵs, such as ecologist David Lamb of the University of Queensland
and Hallam in Melbourne deny that they have cashed in on the koala’s plight.
‘There’s more money coming for koala research, but it’s not a bonanza,’
says Lamb. ‘It’s been difficult, until recently, to get money to work on
koalas,’ adds Hallam. ‘For a country that rides on the back of a sheep,
you can get lots of money for looking at sheep or cattle. But the (official)
reply might be that until we start harvesting koalas, we won’t worry too
much about how they survive.’

The middle ground in this particular argument is represented by Martin
at Monash; he argues that some animals, such as the hairy-nosed wombat and
several bandicoots and native cats, are far more endangered than the koala.
‘We should look at our priorities if we’re going to raise lots and lots
of money to do re search on koalas. Perhaps that’s not such a smart thing
to do because there are other species which are perhaps more deserving of
research at this stage,’ he says.

The final word on the koala debate must go to Ian Hume at the University
of Sydney. He speaks for many Australians when he says that as the nation’s
‘flagship of conservation’, koalas deserve financial, scientific and public
support. ‘They are the highest profile animal that we have. When we save
koalas and their habitat, we are automatically saving habitat for many other,
even more endangered, native fauna.’

* * *

More than one cure for extinction

THE fight to save Australia’s koalas is being waged on three fronts:
in the laboratory, the forest and the political arena.

Microbiologists are striving to identify all strains of chlamydia that
affect koalas. Their goal is to develop a vaccine that can be used to protect
koalas in zoos and game parks from the disease. ¿ìè¶ÌÊÓƵs are also attempting
to find an effective treatment for infected animals.

So far, the most promising drug is trospectomycin, an antibiotic developed
in the US to treat human chlamydia. Other drugs often kill the koala along
with the bacteria.

Biologists and ecologists are collecting field data to help improve
government strategies for managing the wild koalas in Australia’s forests.
They are evaluating the risks and benefits of moving animals from overpopulated
to underpopulated areas of the country, a tactic used in the state of Victoria
since the 1920s.

Other studies are proposed to find out how much land koalas need. The
amount of land needed to sustain those animals living in fragmented or sparsely
wooded areas is clearly greater than in ‘quality’ habitat, well-endowed
with eucalyptus. But as yet there is no reliable method to enable ecologists
to assess ‘quality’ in this sense.

Other biologists are investigating the koala’s highly specialised digestive
system to understand better the animal’s nutritional requirements. This
information could lead to improved diets for captive koalas. At present,
they are fed eucalyptus leaves almost exclusively.

As supplies of the leaves are not always reliable, a variety of dietary
supplements would help to keep the koalas fed and fit. Experts at the University
of Sydney and the Taronga Zoo in Sydney have created a ‘koala biscuit’ that
begins to fill the nutritional gap.

Wildlife officers are encouraging land owners to safeguard koala colonies
on their property, while city planners seek to ‘build’ koalas into rapidly
expanding communities. The planners are trying to introduce innovative designs
that maintain good koala habitat within new residential developments; road
systems that bypass koala territory or force people to drive slowly; and
civic bylaws that regulate human activities and control dogs in koala country.

Most importantly, conservationists and scientists are urging city, state
and federal governments to protect koala habitat. Their message is clear:
the trees cut down to make way for housing, logging and tourism, are home
and kitchen to Australia’s most famous marsupial.