7 Jun 2011

Seabirds and rodents on Australia’s outlying islands

By BirdLife Australia

Rabbits and rodents have wreaked havoc on seabird populations on Macquarie Island, with rabbit grazing destroying albatross habitat and rodents preying on petrel chicks in their nests. Birds Australia has identified Macquarie Island as an Important Bird Area for four species of penguins, four species of albatrosses, Northern and Southern Giant-Petrels, White-headed Petrel and Brown Skua. Measures to reduce the number of introduced mammals on the island are crucial for seabird conservation.

Birds Australia has just received an update on the progress of an ambitious aerial baiting program on the island from Macquarie Island Pest Eradication Manager, Keith Springer. The program began last year, with the aim of eradicating rats, mice and rabbits from Macquarie Island. Unfortunately, bad weather brought a halt to the first phase of the program last July, but operations resumed this May. Hopefully the program will be successful this year.

Rabbit Haemorrhagic Disease Virus was introduced to the island last February, resulting in a significant reduction in rabbit numbers. This should reduce the potential for mortality among scavenging seabirds (primarily giant-petrels and Brown Skuas) which might feed on poisoned rabbit carcasses after aerial baiting. To further reduce the possibility, teams will remove dead rabbits so that scavengers cannot eat them.

Rabbits have caused extensive damage on Macquarie Island. (Keith Springer).

By mid-May this year, 75% of the first bait-drop across the island had been carried out, with the remainder due to be completed soon. Rats and mice also pose a significant threat to another of Australia’s World Heritage listed islands: Lord Howe Island. There is an ambitious plan to eradicate rodents from this island too, to restore it as a safe haven for many birds and other wildlife. Birds Australia recently wrote to the Australian and New South Wales Governments urging them to fully fund the removal of rodents from Lord Howe Island.

It is encouraging to see that the Australian Government has identified the eradication of rodents from Lord Howe Island as a priority in the 2011–12 Caring for Our Country Business Plan, which guides annual investment in national environment projects. Like Macquarie Island, Lord Howe Island is also a designated Important Bird Area. It has globally significant populations of both endemic birds and seabirds: Providence Petrel, Wedge-tailed Shearwater, Flesh-footed Shearwater, Little Shearwater, Red-tailed Tropicbird, Lord Howe Woodhen and Grey Ternlet. The eradication of rodents from Lord Howe would benefit at least 13 bird species — and White-bellied Storm-Petrels and Kermadec Petrels might be able to re-establish nesting colonies on the main island.