Who’s Afraid of the Big Bad Wolf?
Large predators such as wolf, grizzly bear, and cougar have been hunted out of most of North America. As a result the animals that these carnivores once hunted, moose, elk, and even bison have had no experience with these predators. Wolves, grizzlies and cougars have been persecuted less in the last few years and as their numbers increase, they are moving out from some of their refuges, and are even being reintroduced in some areas. Their prey, having lost their fear, often don't recognize the danger they pose until it is too late.
The blitzkrieg hypothesis was put forward more than thirty years ago to explain why more than forty genera of large animals went extinct in North America 10,000 years ago just after humans made their first appearance on the continent. According to this hypothesis the mastodons, camels, horses, and many other large animals had no experience of humans, they had no reason to fear a relatively small, weak biped, and were wiped out before they could adapt. A similar situation exists today in places where wolves and grizzly bears are recolonizing parts of their former range in North America and encountering large animals that have no fear of them.
Joel Berger's study of this novel predator-prey scenario appeared in a recent issue of Science. We spoke with him about his work and its implications for conservation efforts.