Most bears are apex predators, meaning that as healthy adults, they do not have any natural predators. However, the young of many bear species are at risk to several large predators. According to the Washington Department of Fish and Wildlife, cougars, bobcats and coyotes may attack black bear cubs.
Adult polar bears have no naturally occurring predators, apart from other polar bears. Often, such cannibalism occurs when a hungry adult polar bear consumes a cub because no other food is available. However, wolves and other carnivores may consume young polar bears from time to time.
PBS explains that brown bears are also apex predators that sit atop the food chain in their local habitats. Considering that the largest individuals may be 10 feet tall when standing on two legs and weigh up to 1,000 pounds, it is easy to understand why they have no natural predators. These bears are predators themselves, but a large part of their diet is composed of vegetation.
Despite their apex status, bears are vulnerable to humans armed with rifles, shotguns or bows. In some places, humans represent a significant form of mortality for the bears. For example, the Maryland Department of Natural Resources explains that resident hunters harvest between 20 and 92 black bears annually.