Polar bears have evolved to feed on ice seals, specifically seal fat, the highest calorie food source possible. The bears prey on both ringed and bearded seals across their range, but will take other prey when available. Ringed seals, which are smaller, are the most accessible, especially to younger bears and females. Male polar bears also hunt bearded seals, which are much larger. When adult bears are in good shape, they eat only the blubber in order to build up the fat reserves they need to sustain themselves between meals. They leave the carcass for scavengers, such as arctic foxes, ravens, and other bears. All the other foods that polar bears may eat are less predictable.

Most of these foods, with the exception of walrus or whales, don’t provide enough calories to sustain the polar bear’s massive body size or to build up the bear’s own fat reserves.