Behaviorally, black bears are generally much less aggressive than grizzly bears and rely on their ability to climb trees to allow themselves and their cubs to escape predators such as wolves, grizzly bears, or other black bears. Grizzly bears are more likely to rely on their size and aggressiveness to protect themselves and their cubs from predators or other perceived threats. Due to the behavioral differences between black bears and grizzly bears, most bear-inflicted human injuries inside Yellowstone are caused by grizzly bears, usually during unintentional surprise encounters between hikers and grizzly bear females with cubs in backcountry areas. When backcountry hiking, you can reduce the odds of being injured by a bear by: