DULUTH — Researcher Rolf Peterson and a pilot were tracking a lone wolf from a small plane over Lake Superior last week when they witnessed something for the first time: The wolf, trotting along meager ice off Isle Royale National Park, plunged into Chippewa Harbor.

"All of a sudden, this big hole opened up," and the gray wolf went in, Peterson said.

He said he scrambled to retrieve his camera, but missed the shot. However, a photo of imprints in the snow shows where the wolf planted its face and front paws to claw its way out. The wolf emerged from the water after about 10 seconds, soaked and likely weighing up to a water-logged 200 pounds, Peterson said.

The Michigan Technological University research professor was wrapping up the first week of an annual seven-week study, which includes counting the Michigan park's wolf population, estimating the size of its moose population and determining the rate at which wolves are killing moose. The university has conducted the studies on Isle Royale, about 20 miles from Grand Portage, Minn., since 1959.

Before the wolf fell through ice, it had been tracking another lone wolf, Peterson said, the animal howling at one point and appearing "anxious for connections."

After the wolf escaped the lake, the plane continued to track it until it reached solid ice and ran rapidly up and down just offshore. Then the wolf went onto land to roll in snow before returning to the harbor to lope in circles for several minutes, apparently trying to warm its freezing body on the subzero day.

Finally, it lay down in full sun, out of the wind, and began to pick ice chunks from its coat.

In all his years studying the animals on Isle Royale, Peterson said, he had never seen a wolf fall into the lake. Researchers know it happens, and that some don't survive, he said. He said the incident illustrates how critical a wolf's claws are — a human would have needed an ice pick to escape.

"I've always felt wolves sometimes aren't very careful on thin ice, and this sort of was a demonstration of that," Peterson said.

The researcher said that before the wolf fell in, he saw it punch through the ice for a drink of water. "It knew quite well how thin the ice was," Peterson said.

The 2022 Michigan Tech study showed 28 wolves living in the park, twice as many as in the winter of 2020 when the previous survey was conducted. Then, about 1,350 moose were estimated to be roaming Isle Royale.

A survey was not conducted in the winter of 2021 because of the pandemic.