According to the Washington Department of Fish and Wildlife, black bears have very few predators besides humans. Bear cubs are preyed upon by cougars, bobcats and coyotes, but no animals eat adult bears.
Occasionally, male bears prey upon cubs of their own species. Black bears are considered an apex predator, which means they have no predators once they reach adulthood. Apex predators, including black bears, are only considered to have no predators in their own environment. For instance, black bears would be preyed upon by tigers or lions, but they never encounter these animals in their natural environment, so they do not count as natural predators.