People who study animal behavior think they may have found out why wolves hunt in packs: Because ravens are such good scavengers.

Scientists who watched wolves on Isle Royale in Lake Superior came up with the raven-wolf pack theory after puzzling over a question: Why do wolves hunt in large groups when a single wolf can take down a moose?

To find a possible answer, John Vucetich and Rolf Peterson of Michigan Tech and Thomas Waite of Ohio State University examined 27 years of wolf observations on Isle Royale in northern Michigan. Isle Royale, 45 miles long and up to 9 miles wide, sits in the northwest lobe of Lake Superior. A national park, the island supports a population of a few dozen wolves and hundreds of moose. Peterson studied the wolves for more than 30 years, and the researchers used observations from Peterson and his coworkers in the present study.

Peterson’s team witnessed a single wolf killing a moose 11 times, which weakened the notion that wolves hunt in packs because of the difficulty of killing a moose without help. Vucetich, Peterson and Waite used the years of data from the Isle Royale wolf study to calculate that — in terms of energy burned and meat gained — wolves would do best hunting in pairs.