Bear dispersal patterns follow the general mammalian pattern: females are more philopatric and often share a portion of their natal home range with the mother (Reynolds and Hechtel 1984). Males disperse farther, occasionally travelling hundreds of kilometers (Craighead 1994). In the GYE four dispersing males moved an average of 70 km from their natal home range (Blanchard and Knight 1991). This pattern persists despite the fact that both brown and black bears exhibit characteristics of polygyny and polygamy. Females will mate with several males, and vice versa. Male grizzly bears have been demonstrated to breed successfully with more than one female during a single season, and females have been demonstrated to breed successfully with more than one male; producing litters with multiple paternity (Craighead et al. 1995, 1997). Factors other than breeding exclusion therefore, appear to also be involved in dispersal behavior. Black bear dispersal is similar to that of grizzly bears, but the distances involved are less.

High volume roads like the Trans-Canada Highway near Banff are a barrier to grizzly bears, but not to black bears. Grizzlies avoid underpasses, but black bears will use them (Woods et al. 1996). The only effective barriers to grizzly dispersal (other than very large bodies of water) are caused by human activities (Craighead and Vyse 1996). Although grizzlies are capable of long distance dispersal, none of 460 radio-tagged grizzlies have traveled between the large core reserves in the Northern Rockies within the past 25 years (Servheen, pers. comm. reported in Weaver et al. 1996). It is likely that barriers caused by human activities have impeded longer movements since grizzlies in contiguous habitat unaltered by humans often travel this far.