Isle Royale — 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.
https://www.detroitnews.com/story/news/local/michigan/2019/10/05/park-service-looks-solve-mystery-deaths-isle-royale-wolves/2266685001/