One of the most profound impacts on Australia’s island biodiversity in the past 200 years has been the introduction of invasive species. In the case of Macquarie Island, sealers deliberately introduced cats and rabbits over 180 years ago and unintentionally introduced rats and mice.
The impact of introduced predators on wildlife and the vegetation degradation caused by rabbits was severe. Many species were threatened by invasive cats, rabbits, rats and mice. The island currently supports 17 listed species under EPBC with another two listed as extinct. Feral animal control commenced on Macquarie Island in the 1970s, and has been ongoing since then. The last cat was eradicated in 2000, with the complete eradication of all four species declared in 2014. At the time, this was the largest and most expensive multi-species vertebrate eradication program ever attempted in Australia.
The expectation is that the island’s biodiversity will bounce back, yet it is unknown how this will occur for specific species. For example, a native predator, the brown skua, lost one of its main prey source, rabbits, and several hundred were incidentally killed by eating poisoned rabbit carcasses. Monitoring the ecosystem response to eradication will inform the future management of Macquarie Island. Learning from the post-eradication response of Macquarie Island will also provide important insights that can be applied in the planning of other island eradication projects.