Pests eradicated from Macquarie Island

Macquarie Island researchers will no longer wake to the night time scrabblings of rodents around their field huts, with the pests now officially eradicated from the island.

The seven year, $25 million eradication project, funded by the Australian and Tasmanian governments, ended in April this year, with Tasmania Parks and Wildlife Service project manager, Keith Springer, declaring that no rabbits, rats or mice had been detected for the past two and a half years.

A ceremony was held in Hobart on the return of the 12-strong hunting team, including 11 hunting dogs and their handlers, who had spent the past 13 months scouring the 12 785 hectare island for signs of survivors, after an extensive baiting program in 2011.

Already the flora and fauna on the World Heritage listed island is bouncing back, with tussock grasses providing cover for seabird chicks, and megaherbs returning in all their lush, green glory. Some bird species, previously restricted to breeding on offshore rock stacks, such as blue petrels and Antarctic terns, have begun to recolonise the main island. The cause of much of the island’s erosion and deadly landslides has also been removed.

While the news is good, ecologists say it could take up to 20 years before a new ecological equilibrium is reached and the end result is not always predictable. Reports from other island eradication projects indicate that even in the same archipelago, different plant species can respond quite differently to the removal of pest species. However it is clear that significant ecological improvement is the main story from islands where pests are removed.

‘It is exciting to see an ecosystem which suffered significant degradation due to pest species, for more than 100 years, firmly on the road to recovery, and it will be just as fascinating to see how the landscape recovery evolves in the coming decades,’ Mr Springer said.

The eradication program eliminated some 150 000 rabbits from the island in the first year. The release of calicivirus culled numbers initially (in 2011), followed by an aerial baiting program targeting surviving rabbits, as well as rats and mice. Australian- and New Zealand-trained dogs were then brought in to help hunters to finish the job — finding just eight adult survivors of the aerial baiting, plus a single litter of kittens.

‘After the baiting, the island was divided into six hunting blocks, with teams of two hunters dispatching rabbits using detection dogs, spotlighting, burrow fumigation and trapping,’ Mr Springer said.

‘In 2013 two New Zealand rodent dog handlers and their three rodent detection dogs joined the team specifically looking for evidence of any surviving rats and mice, and found none.’

The project has generated global interest as it is the first time that rabbits, rats and mice have been eradicated all at the same time, from an island the size of Macquarie Island.

With the island now free of pests, the key is to prevent a reintroduction of pests from ships’ cargo. In 2013 the Australian Antarctic Division opened its new biosecurity facility on the Hobart waterfront. The facility has vermin traps, impenetrable walls and fumigation areas and staff use rodent detector dogs to screen all cargo destined for Antarctica and the subantarctic. On Macquarie Island, rodent and insect traps are laid around the station during and after voyages.

Wendy Pyper
Corporate Communications, Australian Antarctic Division