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Koala chaos! Pest or victim: koalas living on one Australian island are caught in the center of a heated debate.

Each year, thousands of tourists flock to scenic Kangaroo Island in Australia. For many, the trip's highlight would be spotting a fuzzy koala, "A koala's gentle presence seems to melt even the hardest human heart," says Deborah Tabart, executive director of the Australian Koala Foundation (AKF). But for many of the 4,000 people who live on Kangaroo Island, these marsupials (see Nuts & Bolts, p. 12) are far from delightful. They are pests that need to be managed.

The Australian government estimates that the koala population on Kangaroo Island is about 27,000. Some conservationists believe that's too many koalas for the island's ecosystem to handle. To prevent koalas from damaging the island's delicate network of plants and animals, many scientists and residents are calling for a massive koala cull. But the idea of killing a large number of koalas to keep the species' population in check has some people, including the AKF, in protest.

This gentle, solitary animal spends up to 20 hours a day sleeping, and the remaining hours eating eucalyptus tree leaves. So how did it wind up in the center of a charged tug-of-war?

MOVING KOALAS

For thousands of years, koalas thrived all over Australia. But when European settlers arrived in the late 1700s, they hunted millions of the animals for their fluffy fur. In addition, they destroyed as much as 80 percent of the koalas' forest habitat for farmland. With limited living space, and their sole food source--eucalyptus tree leaves--drastically reduced, koala populations tumbled.

"People were concerned that koalas would go extinct," says David Paton, a biologist at the University of Adelaide in Australia. To prevent the species from dying off, scientists introduced 18 koalas to Kangaroo Island in the 1920s.

Before this introduction, the 4,370 square kilometer (1,687 square mile) island was koala free. But it contained all the ingredients to create a paradise for the animal. It was--and still is--sparsely inhabited by humans. The island is also devoid of the koala's natural predators such as wild dogs called dingoes. With lots of food and nothing to hunt the marsupials, scientists hoped the koalas would thrive. In fact, the population exploded.

PICKY EATERS

A koala boom may not seem like bad news. But many people believe the eating habits of these introduced animals are damaging parts of Kangaroo Island.

Eucalyptus leaves are nutritionally poor. To survive, a koala must eat as many as 1,000 leaves each day. When a koala keeps stripping a eucalyptus branch of its leaves, the tree doesn't have a chance to regrow new ones.

The branch dies. "Koalas can kill a tree bit by bit," says Paton. "When that happens, the other animals that depend on the tree for survival suffer." For example, Paton has seen a plunge in the number of endemic (native) bird species in areas where koalas have damaged trees.

Losing eucalyptus trees could also spell trouble for the island's farming industry. "Here, the topsoil is very shallow," explains Paton. The tree roots dig deep into the land to help keep the soil in place. Without the trees, rain could easily wash away the soil, degrading the quality of farmable land, he says.

The koala's giant appetite could also affect future generations of the species. Scientists estimate that the island's koala population will double within five years. "They may eat their way out of a home," says Paton.

CHAOS CONTROL

To control the koala boom, the Australian government has sterilized thousands of island koalas since the 1990s. But tiffs surgical procedure, which stops an animal from being able to reproduce, is costly. "It's also impossible to sterilize enough koalas at any given time to create a sudden drop in the population," explains Paton. The AKF believes this procedure is inhumane, says Tabart.

The government has also relocated hundreds of island koalas to parts of the mainland. But since koalas stress easily, they don't adapt well to the new surroundings. Stressed koalas are prone to illnesses, Tabart explains.

Paton believes that the most effective way to protect Kangaroo Island and control its koala population is to cull as many as 20,000 of the animals.

UNCERTAIN FUTURE

Today, koalas are protected by law. The Australian government has struck down proposals to allow a koala-cull.

Culling one of Australia's national icons will generate a negative image and drive away tourists, says Tabart. The AKF says that the koalas aren't to blame for the failing environmental health of Kangaroo Island. Rather, the organization believes the real culprits are industries, including farming, that have cleared vast areas of eucalyptus forests. The AKF believes better land management will help save koalas and other island species.

But Paton believes that time is running out. That's because it could take years for a eucalyptus tree to grow to a size that could support a koala. Culling, Paton says, can swiftly manage the koala population and give the trees, the endemic species, and the entire ecosystem a chance to recover.

As the debate rages on, koalas on Kangaroo Island continue to multiply. Meanwhile, the island's ecosystem is deteriorating. Will a solution arrive before it's too late?

Nuts & Bolts

In 1814, French and German scientists gave koalas the scientific name Phascolarctos cinereus (FAS-co-LARK-toes SIH-neh-RAY-us), which means "ash-gray, pouched bear." Later, scientists learned that the koala is a marsupi. al, not a bear. Marsupials are mammals that usually feature pouches in which to nurse and carry their young. This protective feature helps marsupial babies, or joeys, survive. That's because joeys are born weak and highly underdeveloped. A newborn koala is blind, hairless, and as tiny as a jellybean.
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Article Details
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Author:Chiang, Mona
Publication:Science World
Article Type:Cover Story
Geographic Code:8AUST
Date:Sep 5, 2005
Words:934
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