A three-part series on bears: their habitat, how to avoid them, and what to do if you encounter one. Eight species of bears exist in the world. North America is home to three: Ursus maritimus,the polar bear, Ursus americanus, the black bear, and Ursus arctos, the grizzly (brown) bear. This article will discuss the two species most likely encountered in North America: the black and the grizzly bear, although the basic concepts of bear safety can be applied in bear territory worldwide.