Image 1 of 2 ▼ (Photo credit: NPS / Jim Peaco)

One of the three gray wolves relocated from Minnesota to Isle Royale National Park on Lake Superior last fall crossed an ice bridge last week and returned to the mainland.

The National Park Service brought the 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 1,400 moose.

WOLF WEEK: Wolves to be reintroduced to Isle Royale

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 fourth, 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 knew there was a possibility the relocated wolves would attempt to return to Minnesota, where they were captured. Early research on wolf relocation found if you move a wolf 80 miles, it would typically try to return home.

“I was excited to see locations after not seeing anything for five days, but that excitement quickly gave way to disappointment as my eyes followed the track that led away from Isle Royale,” Mike Romanski, the project lead for the wolf reintroduction efforts, said in the release. “I knew this could happen but of course you always hope for the best.”

Previous studies also found if the wolves had been held in the release area for three to four weeks, they generally stayed in the area. Researchers say understanding why this wolf decided to go back to Minnesota could provide groundbreaking new information on wolf behaviors.

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.