A remote volcanic island near Antarctica has lost its title as the world's largest penguin colony after new research revealed massive population declines.
Researchers from the British Antarctic Survey (BAS) found that over half a million chinstrap penguins have disappeared from Zavodovski Island in the South Sandwich Islands.
This loss represents over a quarter of the island's penguins, which are almost entirely chinstrap and macaroni penguins, and cedes the title of the world's largest penguin colony to Cape Adare in the Ross Sea.
For years, Zavodovski Island appeared to buck the trend of widespread chinstrap declines reported across Antarctica and surrounding islands.
Remote outpost: Volcanic Zavodovski Island in the South Sandwich Islands, where researchers travelled across stormy seas to document major changes in one of the world’s most important penguin populations. Photo: John Dickens
However, the new study, published this week in the journal Current Biology, shows Zavodovski now has the world's highest rate of chinstrap population decline, with data showing this trend stretches back to 2011.
The steady loss of the penguins suggests the island's March 2016 volcanic eruption, which deposited smoke and ash over the volcano's lower slopes, is not to blame. Instead, the researchers point to climate-driven changes to the Southern Ocean that are disrupting the penguins' food supply.
Because the South Sandwich Islands are home to 30% of the world’s chinstrap population, declines here, along with those seen elsewhere in Antarctica, may push chinstrap penguins into the 'Endangered' category on the IUCN Red List of Threatened Species.
Interestingly, while the chinstrap population has been declining, the macaroni penguin population on the island increased by 28% from 2011 to 2016 and has remained stable since. The researchers also attribute this to the penguins' dining habits.
Chinstrap warning: Chinstrap penguins on Zavodovski Island, where a loss of more than half a million birds has given the colony the world’s highest recorded rate of decline for the species. Photo: John Dickens
Unlike chinstraps, macaroni penguins have a broader diet and can switch to alternative prey such as fish and crustaceans when krill become less abundant. Tracking data showed they predominantly foraged in warmer waters northeast of the island, likely supplementing their diets with these alternative food sources.
The report comes just six months after scientists declared Emperor penguins endangered because of sea ice loss.
The BAS research team sailed for 15 days across stormy seas to reach the rugged cliffs of this volcanic island, about twice the size of Gibraltar and very remote.
While camping on the island, they used a combination of drone surveys, aerial photography (courtesy of an RAF Atlas aircraft stationed in the Falklands), and tracking devices fitted to penguins to assess the status of the colony.
Population declines and changes in community composition at the world’s largest penguin colony by Ratcliffe et al., is published in the journal Current Biology. Find the full article here.
