Because polar bears are apex predators, they have no natural enemies, but when a polar bear male fights another male during mating season, it defends itself with its brute strength, curved claws, powerful jaws and long, sharp canine teeth. In rare encounters with other predators, such as grizzlies, a polar bear tends to back off in defense and leave the carcass to its opponent.
Considered the most powerful land predators on Earth, polar bears dominate the environment of the far north. Their main prey are seals, and their main method of hunting is still-hunting. They wait near a breathing hole until a seal emerges, and then drag the seal onto the ice and kill it.
Full-grown polar bears sometimes hunt much larger animals, including walruses, beluga whales and narwhals. Although they aren't averse to hunting large land animals such as caribou, reindeer and musk ox, this is more difficult for them, as polar bears can't run far without overheating. Polar bears also eat a variety of other foods, including rodents, crabs, birds, eggs, kelp, roots and berries.
The greatest danger to polar bears is climate change. Polar bears require sea ice as a hunting platform, and the amount of sea ice is decreasing. As a result, many polar bears become victims of malnutrition and starvation. The lack of sea ice forces polar bears onto land where they run increased risk of interactions with the industries and habitations of humans.