Macquarie Island declared pest-free

The largest eradication program of its kind has successfully rid Macquarie Island of rats, mice and rabbits.
By Erin Frick April 8, 2014 Reading Time: 2 Minutes

MACQUARIE ISLAND IS officially pest-free, thanks to a seven-year eradication program. After two years of monitoring, the sub-Antarctic island, which is part of Australian territory, no longer has rabbits, mice or ship rats ravaging its unique wilderness.

“The island is the largest and most remote location where the total eradication of three invasive species has been successfully completed,” Minister for the Environment Greg Hunt says in a statement.

Macquarie Island, located 1500km southeast of Tasmania, provides 12,785 ha of essential breeding ground for fauna in the sub-Antarctic region of the Southern Ocean including endangered seabirds and elephant seals.

Macquarie Island free from three pest species

Designated a World Heritage site in December 1997, the ecosystem of Macquarie Island faced severe degradation as the result of introduced rabbits (Oryctolagus cuninculus), ship rats (Rattus rattus) and house mice (Mus musculus) brought to the island by commercial seal and penguin hunters over two centuries ago.

Ship rats preyed on the chicks and eggs of endangered seabirds. Rabbit burrowing and overgrazing depleted the island’s vegetation, destroying the nesting sites of albatrosses, petrels and prions. Widespread vegetation loss (tussock grass, Macquarie cabbage and silver-leaf daisy were especially threatened) caused extensive soil erosion and landslides, one of which killed 100 king penguins.

Macquarie Island pest-eradication the biggest of its kind

The $24.6 million project was the largest and most remote pest removal scheme of its kind ever undertaken. It began with an aerial baiting phase in May 2011, designed to dose the island’s population of 150,000 rabbits and countless rodents with Brodifacoum, a substance found in rat poison. A separate hunting phase followed in July 2011 to eradicate remaining rabbits.

Since August 2011, the island has been scoured by specially trained detection dogs, their handlers and rodent hunters, who after trekking over 90,000 km in search of introduced mammals and their markings, have determined the island to be free of pests.

“The island’s vegetation regrowth is really quite amazing now that the rabbits are no longer grazing,” says Keith Springer, Macquarie Island Pest Eradication project manager. “Wildlife and seabirds such as the blue petrel have begun to breed on the island again after decades of not doing so. They’ve figured out that it’s safe and they aren’t going to be bitten by a rat.”

Despite the rapid response of vegetation and wildlife to the pest eradication, the island as a whole will take far longer to recover. “It will likely take 30 to 50 years for the island’s healing process to return it to a level of ecological stability similar to what it once was,” Keith says.