<P> Grizzlies are considered more aggressive compared to black bears when defending themselves and their offspring . Unlike the smaller black bears, adult grizzlies do not climb trees well and respond to danger by standing their ground and warding off their attackers . Mothers defending cubs are the most prone to attacking, and are responsible for 70% of humans killed by grizzlies . </P> <P> Grizzly bears normally avoid contact with people . In spite of their obvious physical advantage they rarely actively hunt humans . Most grizzly bear attacks result from a bear that has been surprised at very close range, especially if it has a supply of food to protect, or female grizzlies protecting their offspring . A bear killing a human in a national park may be killed to prevent its attacking again . </P> <P> Exacerbating this is the fact that intensive human use of grizzly habitat coincides with the seasonal movement of grizzly bears e.g. in the fall, when grizzly bears congregate near streams to feed on salmon when anglers are also intensively using the river . </P> <P> Increased human--bear interaction has created "problem bears": bears adapted to human activities or habitat . Aversive conditioning using rubber bullets, foul - tasting chemicals, or acoustic deterrent devices attempt to condition bears to associate humans with unpleasantness, but is ineffectual when bears have already learned to positively associate humans with food . Such bears are translocated or killed because they pose a threat to humans . The B.C. government kills approximately 50 problem bears each year and overall spends more than one million dollars annually to address bear complaints, relocate bears and kill them . </P>

Where are bears located in the united states