Can a deer kill a black bear with its bare teeth? On Anticosti Island, a 3,097-square-mile expanse of forested terrain off the coast of Quebec, the answer appears to be yes. The deer didn't develop a sudden taste for bear flesh; instead, they most likely devoured the berries upon which the bears fed to fatten up for winter. Deprived of this vital food, the bears disappeared from the island.
In the 1850s, explorers described a profusion of Anticosti bears living on "rich berries and wild fruits, such as currants and gooseberries." When ecologist Steeve Côté of Laval University in Quebec and his students went looking for berry bushes there, however, they found barely a twig of any of five shrubs once common to the forests. Instead, they encountered a thriving population of 150,000 well-fed white-tailed deer, first imported in 1896 by a landowner aiming to make the island a hunter's paradise. Apparently, the deer had browsed the plants to near eradication.
Côté believes the bears died out because they could find no alternative food in autumn: Salmon are sparse in the region, and by that time of year, deer fawns have grown too large to catch. "To my knowledge, this is the first evidence of what appears to be the indirect extirpation of an abundant large carnivore by an introduced herbivore," he says.
For more about the demise of Anticosti Island's black bears, see "Extirpation of a Large Black Bear Population by Introduced White-Tailed Deer." Steeve D. Côté, Conservation Biology, Volume 19, No. 5, October 2005, pp. 1668-1671. (Download the .pdf.)
To read about the ravaging of the environment by ravenous deer, see "Ecological Impacts of Deer Overabundance," by Steeve D. Côté et al, Annual Review of Ecology, Evolution and Systematics, 2004, Volume 35, pp. 113-147.