Only two of the relocated grey wolves remain on Isle Royale following the first phase of re-population efforts. When researchers returned to Isle Royale following the government shutdown, they confirmed the presence of two of the three relocated, radio-collared wolves on the island, but could not locate the third, according to a news release. The researchers noticed a very static-filled signal radiating off Isle Royale’s north shore towards Canada. They eventually determined the wolf, a female, left the island via an ice bridge that formed during the polar vortex and headed to the Pigeon River on the border between Canada and northeastern Minnesota. Researchers say understanding why this wolf decided to go back to Minnesota could provide groundbreaking new information on wolf behaviors.

The National Park Service brought three wolves to the island as part of their plan to move 20-30 wolves from the U.S. and Canada over the next few years to rebuild the once thriving population. Prior to the relocation, only two non-breeding wolves remained on the island to hunt a growing moose population.

The lone male wolf relocated from Minnesota died in October of unknown causes. The 5-year-old male was among the first two wolves released at the park September 26. A female wolf died prior to release while in a holding facility in September.

Wolves are not native to Isle Royale; scientists believe ice bridges enabled the first wolves to find the island more than 75 years. At their peak in 1980, around 50 wolves roamed the island.