Rare footage from a camera strapped to an Adélie penguin in Antarctica shows that the penguins will go out of their way to eat jellyfish that have large and prominent gonads.
The penguin-cam film was first released a year ago, and scientists have been scouring the footage to learn more about Adélie behaviour. Researchers strapped lightweight cameras to the penguins, which were removed when they returned to nest. The footage shows a rare penguin-eye view of the Antarctic sea.
The penguins' preferred food is krill, and yet when jellyfish with large gonads are available the penguins will happily go for them instead.
"We were surprised to see the penguins go for jellyfish and it raised the question: is this new behaviour for Adélie penguins, possibly developed because they had a hard time finding food during this year of very unusual sea-ice conditions? Or is it simply newly revealed by using this video approach to study their diet?" Jean-Baptiste Thiebot of Japan's National Institute of Polar Science said in a statement.
The gonads are rich in protein, which is one proposed reason for the Adélies' behaviour.
"To clarify this, we will need to see comparisons across different penguin species and different ocean regions," says Thiebot. "But these observations already reveal one more piece of the puzzle in the oceans' food web."
The research is helping the conservation organisation WWF to gather information about Antarctic wildlife in order to create reserves in the Antarctic seas.
"The results give us a better understanding of how they might respond to climate change and related shifts in the Antarctic food web," said Rod Downie, WWF polar programme manager.
A network of Marine Protected Areas would help protect the feeding grounds of Adélies, as well as other penguins, seals and whales in Antarctica, the organisation says.