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The Wolf and the Moose: Natural Enemies That Need Each Other

Landmark project celebrates 50 years of tracking wolves and moose on a protected archipelago in Michigan's Lake Superior
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ISLE IN WINTER

Michigan's Isle Royale is an archipelago in northwestern Lake Superior, close to the Canadian border. Approximately 50 miles (80 kilometers) long and eight miles (13 kilometers) wide, it affords researchers a chance to study the predator-prey relationship between wolves and moose.....[ More ]

ON THE PROWL

Wolves first came to Isle Royale around 1950. It is thought that they walked across an ice bridge on Lake Superior from Canada during an extremely cold winter. The ice bridge has not reappeared since.....[ More ]

DUNCAN BAY NARROWS

The remote wilderness of Isle Royale is preserved as a U.S. National Park. On the archipelago, the wolves are the moose's sole predator, and latter are the former's only prey.....[ More ]

DONS OF THE ISLE

During the 50 years since the wolf–moose study began, only two pilots have flown the small plane that is so essential to the research. Don Murray flew from 1959 to 1981 and Don Glaser has been the winter study pilot since 1981.....[ More ]

COW AND CALF

Moose give birth to 30-pound (14-kilogram) calves in late May, when it is still cold on Isle Royale. During the summer, moose eat enormous amounts of food, up to 40 pounds (18 kilograms) daily. They feed on the leaves of dozens of herbs, ferns, shrubs and trees, increasing their body weight by as much as 25 percent, though most of this bulk is lost during the harsh winter.....[ More ]

FOUR-PACK

In a typical year, Isle Royale is home to approximately 24 wolves. Until this year, the wolves of Isle Royale lived in three packs of three to 11 wolves each. During the 2008 Winter Study, a fourth pack was identified.....[ More ]

HUNKERING DOWN

The 1,000 or so moose on Isle Royale can handle winter's frigid conditions, but the lack of food makes for a hard season on these massive ruminants. During winter, moose mostly eat twigs from deciduous trees and shrubs, along with the twigs and needles of balsam fir and cedar—although these contain only one third of the nutrition of leaves consumed during summer.....[ More ]

KING AND QUEEN

This wolf pack is known as Middle Pack, pictured in 2006. The alpha male is the gray-colored wolf in the center. The alpha female is standing to the right. Alphas lead the rest of the pack as they roam and hunt.....[ More ]

KILL OR DIE

The greatest challenge in a wolf's life is to get enough food to survive another season. Its prey-moose-is dangerous to kill and not always plentiful. A wolf pack typically downs a moose once every four to seven days.....[ More ]

TINY TORMENTERS

Each winter and spring moose are infested with tens of thousands of "winter ticks," a species that feeds only on moose blood. The bloodsuckers cause moose to scratch themselves so vigorously that they have lost much of their hair by winter's end.....[ More ]

FEED FOR ALL

Ravens often scavenge the remains of moose taken down by wolves. The birds can consume as much as one third of a carcass left after a wolf pack has been sated. Because the wolves may only get one chance at eating their prize before the ravens swoop in, the canine predators scarf down an enormous amount of meat in a single sitting—sometimes up to 20 pounds (nine kilograms).....[ More ]

BONEYARD

Researchers on Isle Royale conduct autopsies any time they find a dead moose in order to understand its condition at the time of death as well as the cause of its demise. In more than 50 years of study, bones from about 4,500 moose bones have been collected-the largest compilation in the world.....[ More ]

TOGETHER, FOR NOW

For an entire year, moose calves stay with and are protected by their mothers. But just before their first birthday, when their mother is about to birth again, the calf is rejected and begins its mostly solitary existence.....[ More ]

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