The United States National Park Service says a lone wolf from Isle Royale National Park trekked across frozen Lake Superior before dying near Grand Portage, Minn.

Park superintendent Phyllis Green said a young girl found the female wolf's body while she was playing on the shoreline. The wolf, named Isabelle by researchers, was wearing a collar.

Her death was reported to wildlife biologists, but “they didn't recognize the collar,” Green said.

It was soon determined the wolf had not been collared by researchers in Minnesota or Ontario. The collar was then traced to Michigan — and Isle Royale specifically.

isabelle the wolf

A picture taken by researchers of the lone wolf Isabelle a few months before she was found dead on the shores of a Grand Portage beach. (www.isleroyalewolf.org)

Green said the cold winter created a rare ice bridge from the island to the mainland. She said the last significant ones were formed in the 1990s.

Wolves can travel almost 100 kilometres in a day, Green said. So the 25-kilometre trek from the island to where she was found was relatively short.

Autopsy to be performed

"[Isabelle] was relatively intact, her fur was dry and fluffy, so it didn't look like she'd been in the water,” Green said.

The wolf’s body is being sent for autopsy to find out what happened.

Green said Isabelle had a recent history of being a lone wolf.  Last year she separated from her natal pack and tried to integrate with another.

"That didn't go too well,” Green said. “They basically beat her up a couple times."

Green said it's not uncommon for a wolf to try and find a new pack.

It’s hard to tell how detrimental Isabelle’s death will be to the small population on the island, she added.

“If she were an alpha-breeding female on the island, it would be very, very significant,” Green said.

“The fact that she was a lone female trying to establish that type of role makes her a player — but to the degree, it's not determined.”

It's estimated Isle Royale only has about eight wolves right now — the lowest it's been at any point in the past six decades.