Park service looks to solve mystery deaths of Isle Royale wolves
One year into its effort to reestablish the wolf population on Isle Royale, the National Park Service and its partners have a problem: The new wolves keep dying and nobody knows why.
Since the park service began its relocation efforts in September 2018, 19 wolves have been transplanted from Minnesota, Ontario, Canada and Michigan's Upper Peninsula. Three of the wolves have died, the most recent on Sept. 15. Another wolf left the island for mainland Ontario on an ice bridge in January.
The number of wolves on the archipelago in Lake Superior is now 17: nine males and eight females. Before the repopulation efforts began in fall 2018, there were only two island-born wolves left roaming the island.
As the park service follows the progress of the newly relocated wolves, it is also trying to ensure more wolves don't die so soon after being transported to the island.
Mark Romanski, division chief for natural resources at Isle Royale, said at this point the park service doesn't have many answers.
When dealing with wild animals, Romanski said it's not unexpected that some will die after being transported because the process of capturing and relocating the animals can be stressful for them.
"And although we do everything we can to quickly handle the animal and get them out to the island, of course, each animal is different," Romanski said, "and so they handle stress differently or maybe their capture event was different or different combinations of circumstances."
The park service has now changed its procedures so that the time between the capture of a wolf and its release on the island is less than 24 hours, instead of 36 to 48 hours when the effort began, Romanski said.
Dean Beyer, Wildlife Research Biologist with the Michigan Department of Natural Resources, helps capture wolves that would make good candidates for the move.
Beyer said that wildlife capture and relocation is something that scientists can't totally control and that death is sometimes part of the process. He said it is important to minimize risk for animals when they're captured and handled by members of the DNR.
"We do everything we can do on the front end," Beyer said. "So we develop capture plans and all the people involved in the work have gone through extensive training in terms of how to capture and handle animals and how to chemically immobilize them."
He also said that all the DNR's plans are reviewed by wildlife veterinarians.
One possible factor in the deaths may be a phenomenon called capture myopathy, a complex physiological process that involves high levels of stress resulting in damage to muscle tissues. The breakdown in the muscles can release toxins in the bloodstream which may result in shock, or damage to organs such as the kidneys.
Michelle Verant, a veterinarian for the National Park Service stationed out of Fort Collins, was tasked with monitoring the wolves while they were transported to Isle Royale.
She said that there wasn't evidence of capture myopathy in the first wolf that was tested by the park service, but said that doesn't necessarily rule it out.
"And then this final wolf, thankfully we were able to collect that carcass pretty quickly and it is currently at the National Wildlife Health Center getting a full necropsy," Verant said. "And we may get some evidence there to suggest whether capture myopathy was involved."
Here's what the National Parks Service knows about the death of three wolves transported to Isle Royale:
The first wolf, a male from northeast Minnesota, died in October 2018, about one month after being transported to the island. The park service wasn't able to retrieve the carcass until a week after he died because it didn't have personnel on the island.
The carcass of the wolf was sent to the National Wildlife Health Center in Madison, Wisconsin, where they performed a necropsy. The lab determined the wolf died of pneumonia, but the park service doesn't know how the wolf contracted the illness.
The second wolf, a male from mainland Ontario, likely died in early April 2019, after being transported to Isle Royale in late February. The park service wasn't able to retrieve the carcass from the swamp it was in until May, at which point the carcass was too far decomposed to send in for necropsy.
Romanski said there wasn't external evidence of the wolf getting into some kind of fight, though the park service doesn't ultimately know what happened to him.
The third wolf, a female from the Upper Peninsula, likely died on Sept. 15 when a mortality signal was sent from her collar. She had been moved to the island on Sept. 13 and was recovered by park service staff on Sept. 17.
The carcass was submitted to the National Wildlife Health Center for necropsy Sept. 24.
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