CANBERRA, Australia – Scientists hope to test a contraceptive dart next year as a new weapon to curb a koala population explosion that has destroyed thousands of trees on an Australian island, a researcher said Sunday.
Without predators such as dogs, life on Kangaroo Island off South Australia state has proved too idyllic for the teddy bear-like marsupials' own good.
The tastiest species of eucalyptus on the island are groaning under the weight of an estimated 28,000 koalas that are chomping themselves out of habitat at a rate of almost one pound of leaves each day during the few hours they spend awake.
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University of New South Wales researcher Cathy Herbert said field testing under way on the island of an experimental contraceptive device that is implanted between the shoulder blades of female koalas has proved 100 percent successful.
The device is easily inserted under the skin without sedation in the same way that a veterinarian implants a microchip in a domestic pet, she said.
It is expected to block reproduction for two years through the slow release of a hormone, Gonadtrophin, which is commercially marketed as a contraceptive for dogs.
But while implanting the device in dozy koalas in the field has proved simple, coaxing them out of tree tops where they spend most of the day snoozing up to 100 feet above ground can take more than an hour, Herbert said.
"We're developing a system where a contraceptive implant can be darted into the animal's thigh muscle every couple of years so you don't have to climb the trees, which is quite intensive work," Herbert said. "The remote delivery system should be ready sometime next year for trials in the field."
The researchers work with state government wildlife officers who scale the trees using ropes and pulleys until they're high enough to wave flags on long poles above the koalas' heads. The koalas usually slowly retreat down the trees away from the flags and are easily bundled into bags when they reach the ground.
"Where we're working on Kangaroo Island, the trees are really tall and you can see the koalas way up in the tops blowing around in the wind," Herbert said. "It's quite amazing; they go right to the tips even when it's really windy."
Various research projects have received government funding over the past decade in search of humane and cost-effective methods of reducing the overpopulation crisis on one of Australia's largest islands.
Koalas did not exist on Kangaroo Island until the 1920s, when 18 were introduced in a bid to create a protected haven after the species had been wiped out on the state's mainland by fur hunters and tree clearing.
Any talk of culling Australia's cutest native animal has brought howls of protest, and governments have ruled out that option.
Surgical sterilization and relocation have been tried, but the state government regards these options as too expensive as large-scale solutions.
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