ISLE ROYALE, Mich. (WJMN) – Evidence collected over the last year reveals new information about the wolf and moose population on Isle Royale National Park.
Researchers with Michigan Technological University returned to the island for the first time in two years for a seven-week expedition between Jan 25 and March 6.
Evidence showed at least five litters of wolf pups born on Isle Royale since wolves were brought to the island between 2018-2019. The wolf population on the island has doubled since the last study and now stands at 28.
Sarah Hoy, PhD who was a co-leader of the Isle Royale wolf-moose study said, “The wolves are the only predator of moose on the island and so the moose population had increased really, really rapidly without any wolves. Because moose are such large animals, they can eat up to 40 lbs of vegetation a day in the summer. When you have a really large amount of large animals it can really impact the forest. The park service decided to reintroduce wolves to the island. Part of the aim was to reduce the number of moose which in turn would kind of reduce browsing pressure on the forest.”
The moose population is down from 1,876 is February 202 to 1,346 at the time of the latest study. It’s a decrease of 28%. Part of the decrease is credited to wolf kills which contributed to a little less than nine percent of moose deaths in the last year. Other contributing factors are ticks and a food supply shortage in the winter.
“I think the forest, based on our surveys of the forest this past winter and spring, balsam fir which is the main food source for moose during winter was kind of in quite bad condition because of intensive moose browsing over the last few years.” Hoy continued, “So that was kind of a bit of a surprise. We’d hoped that it would start to improve but it still seemed kind of bad. But hopefully next year with the reduced number of moose we’ll see an improve in the growth of those trees. It also seemed to have been a pretty bad year for winter ticks, they’re a parasite of moose. We see a lot of moose that kind of lost hair because they have a large number of these parasites feeding on them. You usually see that every year but this year it seemed quite bad to other years. So there’s lots of different stressors on the island that impact the number of moose on the island so does the wolf predation obviously but there’s also kind of a shortage of food and then we have parasites on top of that. And so those three things working together is probably why we’ve seen kind a rapid decline over the years in the number of moose on the island.”
The full release including the full wolf and moose report can be found here.