Competition and interaction with other carnivores

Specialization among top carnivores has lead to differentiation of prey and habitat selection. No other carnivore in the western United States replaces the ecological role of the wolf (Schullery, 1996). Wolves and bears tend to avoid each other. Altercations between bears and wolves are not unusual however, and most often occur around kill remains because carnivores scavenge as well as kill prey (Mech et al., 1998). Wolves easily chase off most competitors at a kill, however it is not uncommon for a bear to chase a wolf off of its own kill. There are cases where wolves attack and kill bears, particularly cubs (Mech et al., 1998), but often, older bears face and challenge the wolves, and in this case it is likely that the wolf pack will give up and wait for an easier hunting opportunity. Wolf kills affect other carnivores in the ecosystem because they provide an extra food source. Wolves provide food not only for themselves but also for most of the smaller carnivores and scavengers. There has been some indication that increased wolf kills during the winter create a seasonal food resource for grizzly bears, and thus precludes the bears' need to hibernate (Lime et al., 1993 cited in Estes, 1996). With the presence of wolves on the west side of Glacier Park in Montana, a few male bears have been staying active all winter, rather than retreating to a den, because there are more leftovers to scavenge (Chadwick, 1998).

Wolves may affect cougars directly by running them off kills, which forces cougars to kill more in order to survive (D.H. Pletscher, pers. commun. Cited in Estes, 1996). Wolves may sometimes compete with the fox or lynx, however for the most part they do not significantly affect each other's populations as prey selection has specialized.

Wolves have a history of interacting with the coyote. At one time gray wolves may have limited coyotes (Sargeant et al., 1993 cited in Estes, 1996). With the decline in wolf numbers, a corresponding increase in coyote density was observed. Wolves are also known to hybridize with coyotes in the wild (Wydeven et al., 1998). Wolves and coyotes breed when wolf density is low relative to coyotes. Breeding of female wolves with male coyotes was reported in eastern Canada through examination of mitochondrial DNA (Lehman et al., 1991 cited in Wydeven et al., 1998). This interbreeding and mixing of DNA is harmful to wolf populations and is bad for wolf reestablishment. This concern must be recognized with reintroduction, and may be avoided by ensuring substantial wolf density so that wolves are not tempted to breed with coyotes.

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