Damage to Structures
Wolves are not know to damage structures.
Damage to Livestock and Pets
The ability of wolves to kill cattle, sheep, poultry, and other livestock is well documented (Young and Goldman 1944, Carbyn 1983, Fritts et al. 1992). From 1975 through 1986 an average of 21 farms out of 7,200 (with livestock) in the Minnesota wolf range suffered verified losses annually to wolves (Fritts et al. 1992). According to the International Wolf Center, in 2013, 65 out of 74,400 farms had livestock depredations in Minnesota. Domestic dogs and cats are also occasionally killed and eaten by gray wolves.
In many instances, wolves live around livestock without causing damage or causing only occasional damage. In other instances, wolves prey on livestock and cause significant, chronic losses at individual operations. In Minnesota, wolf depredation on livestock is seasonal, most losses occurring between April and October, when livestock are on summer pastures. Livestock are confined to barnyards in the winter months, and therefore are less susceptible to predation.
Cattle, especially calves, are the most common livestock taken. Wolves are capable of killing adult cattle but seem less inclined to do so if calves are available. Attacks usually involve only one or two cattle per event. Depredation on sheep or poultry often involves surplus killing. In Minnesota, wolf attacks on sheep may leave several (up to 35) individuals killed or injured per night. Attacks on flocks of domestic turkeys in Minnesota have resulted in nightly losses of 50 to 200 turkeys.
Wolf attacks on livestock are similar to attacks on wild ungulates. A wolf chases its prey, lunging and biting at the hindquarters and flanks. Attacks on large calves, adult cattle, or horses are characterized by bites and large ragged wounds on the hindquarters, flanks, and sometimes the upper shoulders (Roy and Dorrance 1976). When the prey is badly wounded and falls, a wolf will try to disembowel the animal. Attacks on young calves or sheep are characterized by bites on the throat, head, neck, back, or hind legs.
Wolves usually begin feeding on livestock by eating the viscera and hindquarters. Much of the carcass may be eaten, and large bones chewed and broken. The carcass is usually torn apart and scattered with subsequent feedings. A wolf can eat 18 to 20 pounds (8.1 to 9 kg) of meat in a short period. Large livestock killed by wolves are consumed at the kill site. Smaller livestock may be consumed at the kill site in one or two nights or they may be carried or dragged a short distance from the kill site. Wolves may carry parts of livestock carcasses back to a den or rendezvous sites. Wolves may also carry off and bury parts of carcasses.
Wolves and coyotes may show similar killing and feeding patterns on small livestock. Where the livestock has been bitten in the throat, the area should be skinned out so that the size and spacing of the tooth holes can be examined. The canine tooth holes of a wolf are about 1/4 inch (0.6 cm) in diameter while those of a coyote are about 1/8 inch (0.3 cm) in diameter. Wolves usually do not readjust their grip throat area as coyotes sometimes do; thus, a single set of large tooth holes in the throat area is typical of wolf depredation. Coyotes will more often leave multiple tooth holes in the throat area.
Attacks on livestock by dogs may be confused with wolf depredation if large tracks are present, especially in more populated areas. Large dogs usually injure and kill many animals. Some dogs may have a very precise technique of killing, but most leave several mutilated livestock. Unless they are feral, they seldom feed on the livestock they have killed.
Wolves are attracted to and will scavenge the remains of livestock that have died of natural causes. Dead livestock in a pasture or on range land will attract wolves and increase their activity in an area. It is important to distinguish between predation and scavenging. Evidence of predation includes signs of a struggle and hemorrhaging beneath the skin in the throat, neck, back, or hindquarter area.
Scats (droppings) left in the vicinity of a kill site or pasture may be useful in determining wolf depredation. Wolf scats are usually wider and longer than coyote scats. Scats 1 inch (2.5 cm) or larger in diameter are probably from wolves; smaller scats may be from wolves or coyotes. Wolf scats frequently contain large amounts of hair and bone fragments. An analysis of the hair contained in scats may indicate possible livestock depredation. Since wolves feed primarily on big game, their scats are not as likely to contain the fine fur or the small bones and teeth that are often found in coyote scats.
During hard winters, gray wolves may contribute to the decline of populations of deer, moose, and caribou in northern areas (Gauthier and Theberge 1987). Studies in Minnesota (Mech and Karns 1977), Isle Royale (Peterson 1977), and Alaska (Gasaway et al. 1983, Ballard and Larsen 1987) indicate that predation by wolves, especially during severe winters, may bring about marked declines in ungulate populations. It appears that after ungulate populations reach low levels, wolves may exert long-term control over their prey populations and delay their increase.
Human Health and Safety
Two fatal wolf attacks have occurred in North America, in 2005 in Canada and in 2010 in Alaska. In both cases, it is believed that wolves had become habituated to humans and showed no fear of them. According to the International Wolf Center, “The most important action is to prevent the deliberate feeding of wolves by photographers or those acting out of a misguided desire to help wolves.” The risk of wolves attacks on humans is extremely low, but it is not zero. The best protection is to fence garbage dumps and landfills, and dispose of animal carcasses properly. This will reduce the possibilty that wolves will associate humans with food, and overcome their fear of humans.