The full version of the Macquarie Island Pest Eradication Plan - Part A Overview March 2007 can be downloaded as a PDF File (2000 Kb).
Macquarie Island Nature Reserve and World Heritage Area has outstanding global conservation, geological, ecological and scientific values.
A long-term feral animal control program commenced on Macquarie Island in the 1960s resulted in the eradication of the weka, a predatory bird, by 1989 and cats by 2000. The proposed eradication of rabbits and rodents on Macquarie Island is an extension of this program.
The impacts caused by increasing rabbit and rodent populations on Macquarie Island Nature Reserve and World Heritage Area are very serious and there are currently no viable population control options for any of these three species of rabbits and rodents. These impacts include devastating effects upon native fauna, flora, geomorphology, natural landscape values and nutrient recycling systems.
Rabbits favour the large leafy megaherbs and grasses, which have no adaptations to cope with grazing. These vegetation types provide critical breeding habitat for a range of burrowing petrel and albatross species. Rabbit grazing is changing areas of tall tussock grassland to modified forms of herbfield, thereby affecting the breeding success of all burrowing seabird colonies on Macquarie Island. The loss of vegetation also causes destabilisation and erosion of steep peat-covered slopes, which also impacts on albatross, penguin and petrel nesting sites.
Black rats prey on seabird chicks and eggs, invertebrates and also impede plant seedling recruitment. Black rats are identified as an ongoing threat to at least nine bird species that currently breed on Macquarie Island.
House mice feed primarily on vegetation matter and inhibit plant regeneration through seedling recruitment and seed consumption. They are known to predate invertebrate species and may have had a significant impact on invertebrate populations on Macquarie Island. They may also predate burrowing seabird eggs and chicks. On other subantarctic islands they have been shown to feed on chicks of large albatross species.
Up to 24 bird species are expected to benefit from a pest eradication operation on Macquarie Island. Twelve of these bird species are listed as threatened under Tasmanian and/or Commonwealth threatened species legislation. It can be expected that many seabird species would rapidly re-colonise the island given habitat restoration and removal of predatory rodents.
Steep slopes denuded of vegetation have resulted in an increased incidence of landslides in recent years. It is critical that an eradication operation is conducted as soon as possible to halt further vegetation destruction and associated soil instability and to assist the recovery of seabird populations on Macquarie Island.
Recognising the significance of current issues, a Draft Plan for the Eradication of Rabbits and Rodents on Subantarctic Macquarie Island (the plan) was prepared. Australian and New Zealand experts undertook a peer review of this document. The result of this specialist advice is this plan, which using a combination of techniques, will target the three pest species in a single eradication operation. This will achieve the objective of restoring Macquarie Island’s biodiversity and natural systems as much as possible.
This plan provides an overview of the issues resulting from increasing rabbit and rodent populations on Macquarie Island. To address these issues the only viable long-term solution is the eradication of these three last remaining animal pest species. A comprehensive operational plan for an eradication program on Macquarie Island has been developed, and an environmental impact statement on the proposed operation is currently in preparation. The proposed Macquarie Island pest eradication operation will be undertaken during the winter months (May – September) to exploit seasonally low levels of all the target species and their natural food resources. It will coincide with the absence of most of the indigenous species, thus minimising or avoiding any effects on their populations.
The recommended methodology for eradicating rabbits and rodents on Macquarie Island is in two parts: 1. Aerially broadcast pellet baits containing brodifacoum - a second-generation anticoagulant - by helicopter. Use of differential global positioning system computers in helicopters will ensure accurate coverage. This operation is designed to eradicate rodents and to remove in excess of 95 per cent of rabbits.
2. Field teams will follow up on the ground to eliminate individual rabbits surviving the bait drops. These teams will use a range of techniques including daylight and spotlight shooting, fumigating burrows, trained dogs and trapping over a four-year time frame to ensure that rabbits are removed faster than they can breed.
Approvals to undertake an eradication operation targeting rabbits and rodents on Macquarie Island are required under the Australian Government Environment Protection and Biodiversity Act 1999 and the Australian Pesticides and Veterinary Medicines Authority. These approvals will be sought after the finalisation of the environmental impact statement.