Until recently scientists had almost no idea where southern elephant seals went when they left their island homes to spend winter feeding at sea each year.
So Australian, British, US and French researchers glued satellite transmitters to the heads of 85 of the seals and tracked them for months as they swam and dived in search of food.
However, the answer has scientists concerned, because it raises the possibility that the marine food chain close to Antarctica is in decline – and the cause may be climate change.
Seals that lived on South Georgia, in the South Atlantic, stayed close to home, feasting on fish and squid from nearby open ocean waters.
But those from Pacific and Indian Ocean islands, including Australia’s Macquarie Island and France’s Kerguelen Island, which preferred to feed near pack ice close to the Antarctic continent, swam up to 2000 kilometres to find a meal. Seals were also observed diving as deep as 1200 metres.