The largest successful rodent eradication ever attempted. Removing cats, rats, and rabbits from a subantarctic island let seabird colonies recover from the brink of extinction.
NASA Earth Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey, Public domain, via Wikimedia Commons
An Unnatural History
For over a century, Australia's subantarctic Macquarie Island was an ecosystem in catastrophic decline. The trouble began with the arrival of sealers in 1810, who unintentionally brought stowaway black rats (Rattus rattus) and house mice (Mus musculus). Around the same time, cats (Felis catus) were introduced to control the rodents in the sealers' quarters. In the 1870s, another wave of sealers introduced European rabbits (Oryctolagus cuniculus) as a food source. These four invasive species unleashed a cascade of destruction on the 128-square-kilometer island.
The rabbit population exploded, reaching an estimated 125,000 by the mid-2000s. Their intensive grazing denuded entire hillsides of the native tussock grasses and megaherbs that held the peaty soil together. This habitat destruction eliminated nesting sites for burrowing seabirds and caused massive erosion and landslides. Cats preyed directly on native birds, which had evolved with no terrestrial predators. Rats and mice consumed eggs, chicks, and invertebrates, disrupting the entire food web. Two endemic land birds, the Macquarie Island parakeet and the Macquarie Island rail, were driven to extinction.
The Eradication
A phased approach to reclaim the island began in the 1970s. The first target was feral cats. After a long campaign, the last cat was removed in 2000. This prepared the way for one of the most ambitious eradication projects ever attempted: the Macquarie Island Pest Eradication Project (MIPEP). In 2007, the Australian and Tasmanian governments jointly funded a $24.6 million plan to eliminate every last rabbit, rat, and mouse.
The project was a massive logistical undertaking. The primary method was aerial baiting, using helicopters to drop poison baits across the island's rugged terrain. This was done in winter to minimize the impact on non-target native species, many of which migrate away from the island during the colder months. An initial bait drop in 2010 was halted by severe weather, but a full-scale operation in 2011, combined with the release of the calicivirus to reduce rabbit numbers, proved highly effective.
Following the baiting, a multi-year ground operation began. Teams of hunters and specially trained detection dogs, including Springer Spaniels and Labradors, methodically scoured the entire island. These teams covered over 90,000 kilometers on foot, searching for survivors. The last rabbit was found in November 2011. After two subsequent years with no signs of pests, Macquarie Island was officially declared free of rabbits, rats, and mice in April 2014.
The ecological recovery has been swift. Vegetation is flourishing on previously barren slopes, a change visible from space. Seabird populations are rebounding. The Blue petrel (Halobaena caerulea) and Grey petrel (Procellaria cinerea), once wiped out from the main island, have returned and are increasing at rates of 14% and 10% per year, respectively. Other species, like the Antarctic prion and White-headed petrel, are also showing steady population growth.
💡Fun Facts
At their peak, the feral cat population was estimated to kill 60,000 burrowing seabirds on the island each year.
The eradication project was so successful that eight species of seabirds, including the Light-mantled Albatross, were down-listed from their threatened status on Australia's national conservation lists.
The hunting and detection dog teams walked the equivalent of more than twice the circumference of the Earth while searching the island for surviving pests.
Strict biosecurity measures are now in place to prevent re-infestation, including using rodent-detection dogs like "Curly" to inspect all cargo before it reaches the island.
Access to the Macquarie Island Nature Reserve is highly restricted and requires a permit from the Tasmania Parks and Wildlife Service.
Admission
There is no standard admission. Access is almost exclusively via specialist expedition cruise ships departing from Australia or New Zealand, which can be costly.
Accessibility
The island is a remote and rugged wilderness with no public facilities. Landings are made by small inflatable boats (Zodiacs), and visitors must navigate rocky beaches and stay on designated paths.
