Go Wild
Kangaroo Island - Island Life 4/6 - Go Wild
In a grand experiment, animals threatened on the Australian mainland, were released onto an island, which had been isolated for 8000 years. Koalas, platypus, emus, mallee fowl, hairy nosed wombats, ringtail possums and others were shipped to Kangaroo Island off South Australia. The outcomes of the grand experiment have been far reaching and in some cases catastrophic.
Some of the native invaders died out. Others like the platypus appear to be thriving without apparent consequences. But the koalas, no longer restricted to their preferred manna gums, are spreading out across the island, targeting, and demolishing gumtree species previously thought unpalatable to their taste. They threaten not only precious Kangaroo Island species of manna, but also the survival of creatures who depend on its canopy and its nectar.
Scientists are picking up the pieces.
Less than three hundred of the rare Kangaroo Island Glossy Black Cockatoos survive and nesting failures mean only 20 chicks survive to fledge each year. Biologist Lynn Pedler, climbing to hollows eighty feet up, watches over the precious annual hatch of chicks. The chicks face a growing list of predators from the abundant brush tailed possums to other hollow nesting cockatoos recently arrived from the mainland.
Tammar Wallabies are gone from much of their mainland range but are an agricultural pest on the island, where they are eaten for birthday dinners. The quiescent embryos of the tammars are all reactivated on the day of the summer solstice, and all young are born 40 days later. There are an estimated one million tammars on Kangaroo Island.
The Rosenberg Goanna is abundant because there was no aboriginal population. The goannas ate the young of an earlier rabbit invasion and saved the island. In this the most southerly of their range, the goannas survive by incubating their young in temperature controlled termite mounds. Some males eat the young of their own species, and Dr Brian Green is blood testing to reveal the blood relationship of predator and targeted young.
Above all the issues, is the unsolved koala plague. The recommendations of a scientific task force to cull koalas were overturned by a government frightened of the tourist backlash. But the problem doesn’t go away, and on KI the koalas are steadily eating their way through a limited supply of vegetation.
The issue is causing management problems for an island increasingly visited by high spending international tourists. It seems that the wildlife we choose to save has as much to do with politics, economics and sentimentality as it does with science.
Published Dec 6, 2020
