Black bears are the most docile species of bear in North America, and of all large predators, they’re among the least likely to attack humans. However, in the wake of a fatal attack at an oil field in Alberta, Canada, concern is growing over a behavioral morph called the predatory black bear.
Behavioral morphs are variations in behavior that differ from a species’ typical repertoire and are exhibited by a subset of an animal population. Black bear attacks on human beings are exceptionally rare yet do occur. An analysis published in The Journal of Wildlife Management records 59 confirmed attacks by black bears on humans in the U.S. and Canada between 1900 and 2009, resulting in 63 human fatalities.
One of the most frightening elements of this analysis is that fatal attacks seem to be rising precipitously: over 50 of the confirmed fatal attacks occurred since 1960. Of these attacks, 52 were cases where a bear specifically stalked human beings as prey, as opposed to bears defending themselves, their young, territory, or other resources.
Black bears are typically avoidant of human contact, yet human-bear interactions are increasing rapidly as human beings move into wilderness territories for recreational activities such as camping, hunting, and fishing; onto newly developed land; and to extract resources. As humans encroach, so does their waste. Most interactions occur when naturally scavenging bears learn to exploit human resources at campsites and dumps. According to the Algonquin Black Bear Study, heavy metal contamination at dumps — notorious “nuisance bear” feeding grounds — may be partially to blame for the increase of predatory black bear attacks on human beings.
While “never step between a mama and her cubs” is a common caution, most attacks are perpetrated not by mothers, but by solitary males weighing in excess of 250 pounds. These dominant, aggressive individuals commonly display a little known and unsavory natural characteristic — predation on smaller members of their own species.
Predisposed to attack large animals of similar size to humans, these bears also sometimes sustain traumatic brain injury during breeding-season fights with one another. The addition of chronic exposure to toxic heavy metals such as mercury that accumulate in the animals’ brains may result in a perfect recipe for continued and escalating attacks. According to black bear researchers Mike Wilton and Jeremy Inglis, black bears are also “relatively high on the mammalian evolutionary scale, and therefore subject to many of the same types of aberrant behavior as other mammals, resulting from ‘commonplace’ brain dysfunction such as viral infection or tumors.”
Ongoing predatory black bear research has fascinating implications for understanding the interplay between toxicity, brain injury, and aggression — not only in bears, but perhaps eventually in human beings.