Lovable Australian Koalas Threatened From All Sides

Koalas, those lovable symbols of Australia, are being killed off by loss of habitat, dogs, cars, sexually transmitted disease and eucalyptus trees that fight back by producing poison leaves.

“The koala is our most popular national ambassador, but it faces an uncertain future,” said Deborah Tabart, executive director of the Australian Koala Foundation.

“Unless economists join conservationists and recognize the value of our wildlife by considering the environment, the only koalas left will be in souvenir shops.”

Koalas have been threatened since the 1920s, when 3 million were shot for their pelts. They became extinct in South Australia state.

Only rough estimates of the current population are available because the pouched marsupials, often wrongly called bears, sleep about 19 hours a day and roam mostly at night. Various guesses put the number between 60,000 and 400,000, most of them in southeast Australia.

The koala is designated as a rare and vulnerable species in New South Wales and appears to be holding its own only in Victoria state.

“Over the next 10 years, I think the koala has a major problem,” Tabart said. “They’re extremely vulnerable to changes in their local environment and do not adapt well.”

Many of the problems stem from human encroachment.

“Since white settlement, 80% of the koalas’ habitat has been destroyed,” Tabart said.

That makes it hard for the slow-moving animals to find enough food and safe places to live, away from deadly dogs and cars.

Koalas are finicky eaters, relying almost exclusively on the leaves of about a dozen of the 650 eucalyptus species.

The leaves are hard to digest--cardboard is easier--and provide one of the least nutritious diets for any mammal. Even though they eat the equivalent of eight loaves of white bread a day, koalas cannot generate much energy.

Some of the trees make it even tougher, the government’s Commonwealth Scientific and Industrial Research Organization discovered recently.

In an effort to keep their leaves, eucalyptus trees that grow in poor soil produce more toxins than trees in good soil, said Adrienne Clarke, head of the agency.

“The situation can be likened to an evolutionary arms race,” she said. “On one side, the trees have made their leaves foul-tasting and toxic so the koalas won’t eat them, while on the other the koalas have evolved complex digestive systems to deal with the poisons.

“In some areas, where there is good soil, the koalas are winning the war. In other areas, where the soil is poor, the trees are winning. The problem is that areas of good soil are not only attractive to koalas, they are also favored by humans for other land uses.”

Then there is chlamydia, a sexually transmitted disease that affects humans and apparently is carried by most koalas. It is responsible for the main koala diseases: kidney and bladder infections, infertility, blindness and pneumonia.

Chlamydia by itself does not seem to be a problem, said Frank Carrick, a zoologist who studied koalas in the wild for a year, but it flares up “when immuno-suppression occurs, when koalas are stressed.”

Tabart’s foundation, which raises money for koala research, has 2,500 American members. An estimated 10 million people each year see the 50 or so koalas at North American zoos.

One of the foundation’s projects is to provide maps, based on satellite imaging, to help developers avoid the best koala habitats.

By contrast with the koala, that other symbol of Australia--the kangaroo--is so plentiful that hunters kill 4 million a year and an increasing number of restaurants offer ‘roo meat.

Farmers describe kangaroos as pests in a league with locusts, and estimate that the animals cost them $140 million annually. According to government figures, the number in New South Wales alone has risen from 5.5 million in 1988 to more than 9 million.