Monday, November 12, 2018

Fact Check: Are Wolves Ruthless Killing Machines?

A common criticism by those who dislike wolves is that wolves are ruthless killing machines compelled by instinct to take whatever prey crosses their path. To check the reality of this, I dove into the writings of several well-respected wolf experts. It turns out that wolves are discriminating hunters; they have to be since they are not well equipped for hunting big prey. Wolves choose “weaker and naive animals and have their greatest success” with elk calves and older elk, writes Jim Halfpenny, an eminent naturalist and author of Yellowstone Wolves in the Wild.

But getting dinner is not easy—can even be deadly—and most hunts are unsuccessful. Yellowstone wolves, for example, only succeed 21% of the time, according to David Mech and Rolf Peterson, renowned wolf biologists writing in the book Wolves Behavior, Ecology, and Conservation. “In no case, can a wolf merely walk up and kill a healthy ungulate that is more than a few days old.”

In Yellowstone the average female elk killed by wolves is about 14 years old, writes Halfpenny. By that age the elk’s teeth are worn down and less effective. This means the animal does not get proper nourishment and is weaker and more vulnerable to attack.

How do the wolves find a vulnerable animal? “Wolves stalk just like a house cat does,” writes Halfpenny. Wolves want to get as close as possible to an elk herd before starting a chase. Once the chase begins, the wolves sort and sift the herd trying to find a weak animal, one less likely to harm them. Wolves are risk averse and by chasing a herd, may detect a male that has been weakened by defending his females during the rut. Or they may separate a calf from the protection of the herd. Or they may find an animal that is diseased, has been injured, or was born with an abnormality.

But wolves also attack healthy animals, even big male elk with dangerous hooves and antlers. Wolves have a tactic that can turn that healthy elk into a vulnerable one: They attack the elk and before the animal can drive them off, they bite it as many times as possible. Those wounds cause blood loss. “Wounded animals,” writes Halfpenny, “seldom travel far, and wounded animals stiffen up, especially during long cold nights. A previously unbeatable foe may now be an easy target.”  

Whether the prey is healthy or vulnerable, wolves are not well equipped for bringing down big animals. A wolf’s skeleton is not built for killing, write Dan MacNulty, Dan Stahler, and Doug Smith in Yellowstone Science. A wolf’s skull is not designed to deliver a killing bite. A wolf’s front-most teeth are all it has for grabbing prey and those teeth wear out with age. A wolf’s jaw cannot be locked when biting prey. A wolf—unlike a cougar and grizzly bear—doesn’t have the right kind of claws and forelimbs for gripping prey. Finally, a wolf’s hunting ability decreases with age; the best hunters are two to three years old. (The average Yellowstone wolf lives to be four or five. Outside the park the average life span is two to three years.)

To reduce risks and overcome their shortcomings, wolves hunt in packs. Packs with four wolves are more successful than packs with fewer wolves when hunting elk. To take down a bison, a pack needs three times that many members.

Wolves are far from being ruthless killing machines. Wolves know they can die trying to dine, so they look for prey that is less dangerous. But even when they find such prey, wolves fail far more often than they succeed.

Rick's award-winning Deep into Yellowstone and best-selling In the Temple of Wolves are available signed or unsigned on Amazon.

Rick's new book, The Wilds of Agingis available signed or on Amazon.

Photo of wolves and elk by NPS

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