Most Southern Ocean petrels breed during the summer months, but the grey petrel (Procellaria cinerea) is an exception. This robust seabird breeds through the harsh sub-Antarctic winter, hunting for food and raising its chick amidst the sleet, snow and relentless winds of Macquarie Island.
In doing so, grey petrels play an important ecological role, transporting marine-derived nutrients from the Southern Ocean back to land and enriching the island’s coastal and terrestrial ecosystems.
Photo: Sarah-Lena Reinhold
Grey petrels were widespread, although rare, across Macquarie Island in 1911, then later disappeared from the island altogether. Their return was first recorded in 1999, coinciding with cat control and the subsequent eradication of feral cats (Felis catus) by rangers from the Tasmania Parks and Wildlife Service (PWS).
Grey petrel re-colonisation on Macquarie Island has continued following the successful removal of rabbits, rats and mice through the Macquarie Island Pest Eradication Project which was managed by the PWS, in partnership with the Australian Antarctic Division (AAD). In addition to eliminating direct predation by rats on eggs and juveniles, the removal of rabbits has also removed competition for burrows and has transformed the island’s vegetation, enabling the recovery of dense tussock vegetation that provides critical breeding habitat.
Grey petrels lay a single egg in March or April, which hatches in May or June. Chicks remain in their burrows for more than 100 days before fledging in spring. This winter, the wildlife team – comprising AAD Wildlife Biologist Dr Sarah-Lena Reinhold, Wildlife Ranger Karina Sorrell and Ranger in Charge Gemma Rushton – are surveying grey petrel breeding sites across Macquarie Island that have not been monitored since 2018.
Using burrow scopes to inspect nests, the team spends the available daylight hours (inevitably covered in mud) crawling through dense tussock to locate burrows and record breeding activity, including the presence of adults incubating eggs and the occurrence of chicks.
Unfortunately, grey petrels continue to face numerous threats throughout their breeding range. Globally, incidental capture in commercial longline fisheries remains one of the greatest causes of mortality. Climate change is altering oceanic conditions across the Southern Ocean and the distribution of prey, while marine pollution, – including plastic debris, -poses additional risks. Continued efforts globally to reduce fisheries bycatch, eradicate introduced terrestrial predators from breeding sites and the protection and restoration of breeding habitat, remain essential to securing the future of grey petrels and many other Southern Ocean seabirds.
Grey petrel surveys will be conducted on Macquarie Island over several years to produce an updated island-wide population estimate, improving our understanding of the status of this threatened species. These data will provide an important insight to the species’ population trend and help guide ongoing conservation efforts under the Agreement on the Conservation of Albatrosses and Petrels (ACAP). It is part of the work of the multi-agency ‘Macquarie Island Wildlife Monitoring Program’.
