A new video has captured a gruesome and little seen side to polar bears: When times are tough, males cannibalize cubs.

The phenomenon, long known to the Arctic’s native peoples, has been studied since the 1980s. Scientists believe that polar bears eat cubs in the late summer and autumn, when seals, their typical prey, are at sea and less available.

“One of the only things that’s left to eat is, in fact, cubs of various ages,” says Ian Stirling, a biologist at the University of Alberta and Environment Canada. “The footage itself is quite rare, but the event probably isn’t.” (See "Flesh-Eaters: 5 Cannibalistic Animals.")

The raw video, shot in the summer of 2015 off Canada's Baffin Island (map) during a Lindblad Expeditions trip on the National Geographic Explorer, mirrors other scientists’ accounts of polar bear cannibalism. 

The slow-moving cub and the smaller female are no match for the large, fast male, which swiftly goes in for the