This past winter, Isle Royale wolf researchers reported a stunning decline in the number of wolves on the island -- the numbers dropped from 16 to 9 in one year, leaving only one that was known to be female. Now they know why.
Wolves in winter on Isle Royale, 2009 photo courtesy of Rolf Peterson, Michigan Technical University
The researchers reported today that they found the bodies of three adult wolves dead in an abandoned mine shaft. One was a young female, a second one, who could have made the wolves survival possible. John Vucetich, one of the researchers and a biologist at Michigan Technological University, said:
"We found there had been a real catastrophe in early winter, before we arrived on the island in January,” said Vucetich. “There were three dead wolves from the Chippewa Harbor Pack in the shaft: a collared male that we had been unable to locate this winter, an older male—maybe the alpha male—and a female born in 2011.
“There is no way to know how the three wolves ended up falling into the pit, but very likely, accumulating snow and ice played a role in the accident.
“We now understand a major reason for the decline in pack size of the Chippewa Harbor Pack in 2012, and perhaps why we saw such a desultory pattern of travel and low kill rate in this pack,” Vucetich said. The pack seemed to have no “game plan” following the large loss of so many individuals, he explained.
The collared wolf was nick-named Romeo, whom the researchers could not find during their 2012 winter study, although they picked up his collar signal briefly once or twice. They named him that because of his eagerness to mate.
The female was lost at a critical juncture in the wolves history. The shortage of females means the wolves, which have been on the island since the 1950s, may well go extinct. There is one other known female on the island who is believed to have mated, but the scientists won't know that until get a glimpse of pups later this summer.
The National Park Service and wolf researchers across the country are now debating whether or not bring new wolves to the island, or let nature take its course, a critical turning point in the management of the the nation's wildest places.
As for the mine shaft, it dates to the time of the time of the Pittsburgh and Isle Royale Company, which operated in the Todd Harbor area between 1846 and 1853. Park Superintendent Phyllis Green said:
“Random events often play a large role in isolated, island populations and although tragic, information from this event will serve to help us evaluate future management of this population.”