Thousands of southern elephant seals (Mirounga leonina), the largest seal species in the world, have taken up temporary residence again on Macquarie Island’s beaches.
Macquarie Island is a Nature Reserve and World Heritage Area located about halfway between Australia and Antarctica. The island is a very important breeding habitat for the seals.
The female cows gather in groups called harems with their pups. The dominant males will then defend a harem against competing males.
This year’s Macquarie Island temporary human residents, part of the Australian Antarctic Program, have been helping the rangers with lots of elephant seal counting as part of long-term monitoring. At the peak of the seal numbers, it can take over four hours each day to count all the elephant seals, which is usually shared between two pairs of counters. This year, they are also comparing the traditional counting method to abundance estimates derived from aerial imagery.
Southern elephant seals are a threatened species that are protected under Tasmanian and Australian legislation (listed as vulnerable). Annual monitoring has shown the island’s population is experiencing a slow decline.
Although it is difficult to understand the reasons for the population decline, it is likely that the foraging habitat of the population is being impacted by changes to Antarctic sea ice extent due to climate change.
Learn more about the Macquarie Harbour elephant seals here.