During this fall's inaugural wolf-hunting season in Montana, hunters killed the matriarch of a Yellowstone wolf pack that researchers had been studying for more than a decade. Park officials suspect that her mate and three other pack members were also killed. A Los Angeles Times stor y about the hunt claims that wolves are known to kill for "pure pleasure." Do wolves really attack their prey just for the fun of it?
No. When they kill more than they can eat in one sitting, the pack usually comes back for second helpings. Wolves achieve a very low yield on hunting expeditions in the wild; somewhere between 4 percent and 8 percent of their attacks are successful. (Lions, by contrast, manage a kill rate of 27 percent or more when they hunt in groups.) Consequently, wolves are opportunistic hunters. If the chance to kill prey en masse presents itself, they have been known to go after more than they can consume. But they're rarely wasteful. Hungry wolves are not above scavenging, and they often return to their kill—or another animals'—days later. They may even bury the leftovers to hide them from competitors such as wolverines. (This is probably how dogs, which are descended from wolves, got into the habit of burying bones.) Of course, no one can say for sure whether wolves derive "pleasure" from a kill.
Mass kills are rare. Most of a wolf's favorite prey species—ungulates like deer, elk, moose, and caribou—can mortally wound their attackers with one swift kick, so wolves tend to focus on the most vulnerable individuals. It isn't often that a lucky wolf pack happens upon an entire herd of young, sick, or elderly prey. (It does happen, though. When elk transition from winter to spring diets—from woody vegetation to fresh green shoots—they go through a period of weakness and lethargy, which renders them vulnerable to a lupine rout.)
Sheep and cattle, unlike their wild ungulate cousins, lack any kind of defense against wolf attacks. This mismatch can lead to the occasional slaughter, raising outcries from Western ranchers who demand greater measures to prevent wolf attacks. However, wolves only turn to livestock when their natural prey is unavailable, so these killings are infrequent. In 2008, wolves are known to have killed fewer than 200 cattle and sheep in Montana, and 100 wolves were hunted down in response.
Wolves are not alone in displaying an apparent lack of predatory economy. Foxes have been known to kill large numbers of chicken, eating only the head of each victim. (Veterinarians vaccinate foxes against rabies by sprinkling inoculated chicken heads throughout their territory.) Weasels like the back of the head and neck of their avian prey and tend to pile up the uneaten bodies in neat stacks. Raccoons eat the head and the crop.
Dolphins have been observed engaging in the seemingly gratuitous killing of porpoises—going so far as to use sonar to locate the victim's vital organs and increase the lethality of the strike—but experts haven't quite worked out their motivation. Some speculate that the dolphins use the porpoises for target practice, preparing for possible clashes with fellow dolphins who infringe on their territory.
Dogs are the only animal that definitely kills for sport, but that's only because humans taught them to do so. When a farmer finds a few dead chickens killed during the daylight hours with no missing body parts, the neighbor's dog is almost always the culprit.
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Explainer thanks Scott Creel of Montana State University and Tom Talasz of Wolf Song of Alaska. Thanks also to reader Eileen Libby for asking the question.