polar bears
A polar bear and a dolphin carcassNorwegian Polar Institute

Polar bears have been documented eating dolphins for the first time and subsequently freezing the leftovers to keep for a feast later.

Researchers first recorded the fact that the polar bears were eating white-beaked dolphins – which they believe had ventured too far north as a result of climate change – in 2014 when a team from the Norwegian Polar Institute, led by Jon Aars, were documenting a group of islands close to Norway.

polar bears
A polar bear devours one of the carcassesNorwegian Polar Institute

The team came to the conclusion that the large bears caught the marine mammals using the same technique they employed to catch seals – by hovering above the ice and waiting for them to come up for oxygen through a hole.

However, the bear which they first saw eating a dolphin, in April of last year, actually bit off more than it could chew and killed two. It then buried one of the white-beaked dolphins under the snow which the researchers believe was to prevent it from rotting.

"We think he caught the second dolphin because he could, and then had extra food later," Aars told New Scientist. "We were surprised as dolphins have not been reported in that area before."

The team wrote in their research paper published on Polar Research: "When observed [the polar bear] was in the process of covering the mostly intact second dolphin with snow. Such caching behaviour is generally considered untypical of polar bears. During the following ice-free summer and autumn, at least seven different white-beaked dolphin carcasses were observed in or near the same area."