Watch a bull elk chase a wolf in Yellowstone National Park. "A single wolf has about a 2% chance of killing an adult elk by itself." (Packer and Ruttan 1988). And that is not differentiating between an adult cow and a bull elk such as this one. The success rate of wolf chases with pack members is only three to 14 percent. "Wolves fail as hunters more often than they succeed," Stevens wrote in the New York Times, "Their main prey species have evolved with them, and so developed formidable defense