Ecology 6th Edition by Charles Krebs

Exercise 7

Grizzly bears and black bears eat the same foods and live in similar places in North America. Grizzly or brown bears are much larger than black bears and more aggressive. All large islands off the coast of British Columbia and Alaska have either black bears or grizzly bears but no island has both species (Apps et al. 2006). Is this evidence for competition between these two bear species? What other evidence would you look for to show that grizzlies affect the local distribution of black bears?