KOALA STERILIZATION AIMED AT PRESERVING TREES.

Byline: Clyde H. Farnsworth The New York Times

Eucalyptus trees with peeling gray and beige bark drape tangles of bushes along the dry flats of the Cygnet River north of this township.

Drew Laslett, a wildlife officer, points at a type of eucalyptus known as a manna gum where a male and female koala, brown-furred and gray on the underparts, are in separate high forks, warily looking down through a fringe of frayed branches.

``That's their ice-cream tree,'' said Laslett, head of a project causing contention here on Kangaroo Island, southwest of Adelaide, and throughout Australia.

He is in charge of the sterilization of koalas, whose numbers have increased so sharply that they are killing the trees on whose mildly toxic leaves they depend for food.

Destruction of the eucalyptuses not only threatens the koalas with mass starvation but also makes the cracked soil less resistant to erosion and flooding, and hurts insects, birds and other creatures nurtured by the same boughs and leaves.

The cost of the sterilization program is at least $500,000 over the next 18 months. Though a relatively modest amount, many local residents say the money is wasted.

``Taking a gun is the cheapest way,'' said David Bell, a retired airport supervisor with a small farm near here. ``A few farmers could have handled the problem quietly. Now we've got all this fuss. It's just a big public-relations exercise.''

Animal-rights supporters say it's outrageous to subject koalas to the ordeal of capture and surgery.

``We're terrorizing the koalas,'' said Leighton Booth, who works in the kitchen of an island hotel. ``This situation is not their fault, but ours. We've cultivated too much of the land and introduced too many sheep. People should be out planting trees, not roping koalas.''

Koalas were introduced to Kangaroo Island only 70 years ago, along with platypuses, brush turkeys and wombats. Kangaroos were already plentiful. Koalas flourished in the new habitat, free from any natural predator. Foxes, like rabbits, introduced for the hunt on the mainland, never made it to the island, and the economy remained rural.

But koalas are a little like rabbits when it comes to reproduction. Nobody knows exactly how many are living here, but official estimates place the number at 5,000, compared with 18 in 1923 and a human population on the island today of 3,500.

The program envisions relocation to suitable habitats on the mainland and to world zoos that often clamor for koalas.

But Barbara St. John, a scientific officer who works with Laslett in South Australia's Department of Environment and Natural Resources, says the numbers are too great for relocation alone as a solution. ``Only a large-scale fertility control program will reduce the future birth rate of koalas,'' she said.

The killing option is rejected by the South Australian state government.

The two wildlife management officers were in the Cygnet River Valley with a group of volunteers led by Scott McDonald, a local schoolteacher, who had organized three teams of five young men and women each to get the koalas down from the manna, blue-gum and other stricken eucalyptuses.

Climbers use a kind of lasso and then with tugging, poling and the waving of a red flag above the animal's head, they encourage it to descend.

In the manna gum, the male and female, gripping branches with their two-thumbed hands, are not at all happy about the sudden attention. It takes nearly half an hour to get each of them to the ground and into waiting burlap sacks unhurt. Though unusually gentle, koalas, when agitated, can bite and claw fiercely.

Tim Lashmar, 19, and Scott Redden, 18, both from the island and considering forestry careers, succeed in nudging the male down.

Lashmar is bitten on the thigh as he grabs the animal to tag the ear. He grins and says, ``Only a pinch.'' Later the animal will get a permanent ID from a microchip with a bar code embedded in its shoulder.

Next step is the nearby trailer that a local veterinarian, Dr. Greg Johnsson, has converted for surgery.

His nurse, Nadia Jackson, holds an anesthesia mask over the furry faces as he performs a vasectomy on the male, then a tubal ligation on the female. Each operation takes 10 to 15 minutes. When the koalas wake up, they are returned to their original trees.

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Photo

Photo: Dr. Greg Johnsson, left, performs a vasectomy on one of Kangaroo Island's koalas Thursday as nurse Nadia Jackson assists.

The New York Times