HOUGHTON, Mich.--After several years of concern about whether wolves would survive the ravages of canine parvovirus on Isle Royale National Park, park officials and researchers have now turned the focus of their attention to the island's moose herd.
Park Superintendent Douglas Barnard says that a survey of moose and wolf populations completed this winter shows only about 500 moose on the island, compared to an estimated 2,400 in 1995. "We knew that we lost a lot of moose during the especially long, harsh winter of '95 - '96," says Barnard, "but no one anticipated that losses would be this dramatic. After completing field work on the island in March of 1996, biologists estimated that there were 1,000 to 1,200 moose within the park. By then, surviving moose were severely stressed from lack of food, deep snows, and a heavy infestation of winter ticks. The moose population was dealt yet another blow, the late arrival of spring greenup, which resulted in additional moose mortality from starvation.
Dr. Rolf Peterson, a wildlife biologist at Michigan Technological University, conducts the annual survey for the National Park Service. Peterson notes that the park's moose population had grown dramatically over the past 15 years. This was due to a population crash in '81 - '82 of their only predator, wolves. That wolf decline coincided with the arrival of canine parvovirus in the region. The dynamic relationship between moose, wolves, their environment, and available food sometimes results in extreme population fluctuations.
"The carrying capacity of the moose range on Isle Royale has been greatly exceeded, resulting in serious overbrowsing that grew worse each year as moose continued to increase," says Peterson. "The length of last winter proved especially costly for calves and older, weaker moose, but it also killed a surprising number of young adults."
Peterson says the only thing that saved most of the moose that survived was an abundance of balsam f
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Contact: Rolf Peterson
ropeters@mtu.edu
906-487-2179
Michigan Technological University
16-Apr-1997