While one mystery was solved, another mystery looms, but may never be solved.
A necropsy performed by pathologists at Colorado State Veterinary Diagnostic (CSVD) on “Isabelle,” the lone grey Isle Royale wolf found dead on the shore of Lake Superior in Grand Portage, determined that a lightweight pellet shot from an airgun killed her. But who shot the pellet may never be known, said Isle Royale Superintendent Phyllis Green.
The radio collared wolf, nicknamed “Isabelle” by Michigan Tech University (MTU) wildlife researchers Rolf Peterson and John Vucetich, crossed a 14-milelong ice bridge between the island and the mainland sometime after January 21, the last time researchers saw her alive.
The lone female was 5 years old and part of a predatory/ prey study by MTU that has been ongoing for the last half century.
Not part of a pack for the last two years, the lonely wolf was found dead on February 8, 2014 by 11-year-old Alyssa Spry, who was out for a walk on the beach near her Grand Portage home. Her father, Chad Spry, contacted the authorities.
The pellet was shot from an airgun more typically used for squirrel hunting than shooting larger animals, said the pathologists, but it travelled between the wolf ’s ribs and into her chest.
“If the pellet had hit just a half inch to the left or right, the outcome may have been less significant,” said National Park Service Chief Veterinarian Margaret Wild.
This winter’s extreme cold allowed for an ice bridge to form and Vucetich and Peterson were hoping wolves would use it to get to the island and replenish the breeding stock. There are only six or seven adults and three pups left on Isle Royale. In the early 1980s there were about 50 wolves.
Meanwhile there are about 1,000 moose on the 51-mile-long island that encompasses about 200 square miles of land. A healthy wolf population in the past has helped to keep the moose herd down and prevent overgrazing of the island’s trees, shrubs and grass.
“Wolf movement to and from Isle Royale National Park across ‘ice bridges’ during extremely cold winters has occurred historically, but is not common,” said Green.
“The studies at Isle Royale have helped us know these wolves on an individual level and this is the first insight we’ve had into travels of a wolf after leaving the island. This year, several ice bridges formed, and the natural movement of the lone wolf from Isle Royale is not surprising,” Green added.
Interaction with wolves and humans is rare, but can be a problem, especially if homeowner’s pets are being threatened, Green said. If the wolf or wolves can’t be scared away, the National Park Service recommends that people contact their local Department of Natural Resources and make sure to obtain proper permits or permission in dealing with a nuisance animal before taking aggressive action. Good advice, but too late for Isabelle.
“The citizens who let us know where this wolf died have helped us obtain the final chapter for this wolf, and we thank them,” said Green, adding, “Most wolves depart leaving only a paw print or a howl in the night and little knowledge of their death. The studies at Isle Royale have helped us know these wolves on an individual level and this is the first insight we’ve had into travels of a wolf leaving the island. No matter how collared wolves die, citizens who inform local authorities of their location help us gain knowledge that may help us manage wolf/human interactions in the future.”
Initial tests revealed that Isabelle was not infected with rabies or the canine distemper virus. She had also eaten recently, but pathologists said she didn’t have much fat in her body, suggesting that this lone wolf was struggling to survive.
Isabelle’s remains will be returned to Michigan Tech where follow-up work will be conducted, including a detailed examination of the skeleton for congenital spinal abnormalities. Once completed, Isabelle’s remains will be archived and available for further research with the bones from 78 other wolves collected over the years.
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