Polar bears are generally voracious meat-eaters so much so that they show cannibalistic behavior at times. They become the predators of themselves. That is to say that polar bears eat polar bears. It happens quite often when adult male bear (boar) wanders around and it finds a female (sow) den with cubs in it. The soar is most likely to kill and possibly eat cubs. The boars are greater in strength as compared to sows.
Although the mother bear tries her best to drive the adult male away the latter becomes too hungry to give up. The mature male is nearly twice the size of an adult female. Thus the female stands no chance to compete with the male. As a result the mother gets injured while the cubs get killed. Boars will grab the dead cubs and eat them.
Polar Bear Cannibalism
Sometimes the younger bears also become the victims of adult bears. Very few researchers have been able to grab photos of a polar bear eating its cubs. Although male bears are far more aggressive and are infamous for cannibalism female mothers also eat their cubs. The cannibalism in female occurs when the mother cannot feed twins or three cubs.
During nursing the sows remain hungry sometimes do not eat for months. However they do have a breaking point beyond which sows are likely to become the predator of her cubs. She sacrifices one of her cubs and eats it to keep herself alive. The cannibalism in female polar bears is extremely rare because they are devoted mothers.
Researchers also observed cannibalism in adult polar bears in the southern Beaufort Sea. These mature bears eventually became too weak to hunt seals. As a consequence they started eating their own cubs. Scientists blame climate change for increasing cannibalism in polar bears. According to them the sea ice is breaking up earlier than ever in the Hudson Bay leaving many polar bear cubs susceptible to cannibalism.