Isle Royale wolves
M183 was found dead on a trail near the center of the island in October 2019.

By Tanda Gmiter

Isle Royale, MI – It was a year ago this month that a National Park Service ranger was on his last patrol of Hatchet Lake Trail, near the middle of Isle Royale, when he came upon the body of Male 183, the park’s last male island-born wolf. The dead wolf was lying on his side on the trail, looking almost like he had stretched out for a nap. But a necropsy would later show the wolf known by his shorthand identifier of M183 had been attacked by other wolves – big predators who have been brought to the island in the last few years to create new moose-hunting packs.

Crushing bites had caused internal hemorrhaging. Other injuries included cracked ribs and broken spinal vertebrae. Researchers estimated the old wolf – who for years before the newcomers arrived had been the only male wolf on the island – traveled a good distance after that attack before he laid down and died near the edge of his territory.

The fact that he died in a very visible spot on that trail – and that NPS District Ranger Michael Ausema happened to be hiking there just a day or two later on Oct. 17, 2019, turned out to be an incredible gift to the scientists who have studied Isle Royale’s wolves for more than 60 years.

Isle Royale wolves
Male 183, the last male from the “original” Isle Royale population. This photo was taken in 2019 when he was traveling with his mate/daughter.

“This just never happens. We were quite jubilant,” said Rolf Peterson, a longtime research professor at Michigan Technological University who co-leads the annual Isle Royale Winter Study. It’s the longest-running predator/prey study in the world. Its primary work is to track the populations of the wolves and moose who live on the remote island wilderness in Lake Superior, about 60 miles northwest of the Upper Peninsula’s mainland.

Unless they are radio-collared, dead wolves are almost never found on the island, Peterson said. So to find a wolf of such significance to the island’s history – the last male of the old Chippewa Harbor Pack – within such a short time of his death was a stunning discovery. In the last year, research on M183′s bones has proven to be a treasure trove of genetic information for scientists who had observed this wolf and its mate since they were pups.

Let’s take a tour of what they learned:

Isle Royale wolves
Scratch marks on a trail – a mark of an excited wolf – were seen near the body of M183 when it was found in October 2019.

An Amazing Discovery

The NPS ranger who found M183 was on his final trail patrol of the season, getting ready to button up the national park as it was closing after a summer of hosting multi-day hikers and day-trippers alike. But getting the wolf’s body out of there would take some planning. The ranger was on foot and it took him another 24 hours just to reach the park’s headquarters.

“It’s incredible. It was just a miracle that he ran into it,” Peterson said. A couple days later, a transport team arrived nearby and hiked in to the spot where the wolf lay. Ravens had already taken his eyes, but the rest of him was relatively untouched. “We had to carry him out,” Peterson said, noting the wolf was an awkward load. “We had several people take turns.” M183′s body was frozen and sent to a lab in Wisconsin for a necropsy.

At first, the recovery team was not sure what had killed the wolf. Peterson said M183 weighed only about 65 pounds at the time of his death, which made him about 20% underweight. But the lab exam revealed a handful of internal injuries the researchers had not seen from the outside.

Isle Royale wolves
The wolf carcass was largely undisturbed except for light feeding by cautious ravens.

“A younger wolf may have survived those,” Peterson said. “But he was ancient.” M183 was 11 years old. The necropsy showed the old wolf had already been living with an age-related arthritic condition in his back and feet that would have meant constant aches and pains. Researchers who’d been watching him for years believed his health had been slowly declining. He seemed to tire easily. For the last couple years when traveling with his mate – a younger wolf called F193 who was also his daughter and half-sister on his twisted family tree – the older wolf would often follow her. When she stopped for a break, he’d lay down. In his prime, M183 would probably have weighed around 80 pounds. But at the time of his death, he was more like a 90-year-old man in human years.

“In addition to being old and perhaps not as nimble as a challenger, his declining condition would also be evident to other wolves,” Peterson said of the attack.

Researchers aren’t sure where M183 was attacked. He may have fought with one wolf, or more likely with a couple. Despite the old wolf’s age, it was likely not a one-sided brawl. “Oh for sure,” Peterson said. “I don’t think he would give up without a fight.” Most wolf-on-wolf attacks are not immediately fatal, and he thinks M183 may have made it some distance before he collapsed.

Isle Royale wolves
The cause of death was not obvious, although M183 seemed very thin and underweight. Evidence of light bleeding could have been caused by scavenging ravens. M183 was 11 years old when he died, and some of his teeth were heavily worn, cracked, or missing.

Very near his body were signs another wolf had found him, too – maybe even the one who had delivered the fatal injuries. Excited scratch marks were clawed into the dirt trail, and wolf scat was found nearby. It’s being analyzed to see if can be linked back to one specific wolf, which would add another twist to the drama that ended this branch of the island’s packs.

M183′s mate, the last island-born female, was not seen during this past winter’s survey. Researchers suspect she might be dead, too. Neither she nor the old wolf were radio-collared, so if she is dead, finding her remains would be a challenge. A bone-hunting effort is being planned for next summer on Isle Royale, and finding hers would be a coup. As the island’s study team has discovered, wolf bones yield a wealth of information.

Isle Royale wolves
M183’s incisors showed pitting of enamel which may indicate poor mineralization of enamel early in life.

What M183′s Bones Revealed

The old wolf’s remains where shipped back to the National Park Service from the Wisconsin lab earlier this year. They were transferred toMichigan Tech in Houghton, where Peterson took his time poring over them and the necropsy findings. “He probably had more evidence of arthritis than any wolf I’ve ever looked at,” Peterson said. Here is what else M183′s bones revealed:

· His teeth had serious issues. Heavily worn and broken teeth suggest that most heavy chewing occurred on his right side.

· Pieces of his tooth enamel had been lost from scattered places on this third incisor, suggesting shortcomings in enamel, which forms early in life.

· There was serious loss of enamel that accelerates tooth wear on his lower left canine.

· Loss of premolars was slowly resolving as new bone formed.

· His hip joints were fine. The head of his femurs showed a nice, shiny and nearly friction-free joint surface.

· Osteoarthritis (OA) is a common pathology in older mammals, including humans. In humans, the most common sites for OA are the hips, knees, and hands. M183 had it in the “hand” equivalent – the phalangeal bones proximal to his claws.

· Most of his thoracic vertebrae were arthritic, although none had fused together.

· He had 28 vertebrae, one more than normal. Extra vertebrae became much more common among Isle Royale wolves as inbreeding reached high levels in the 1990s and 2000s.

· He also had a broken spinous process on his 6th lumbar vertebrae. This was a result from the wolf attack just prior to death. It had not started healing yet.

· His 8th lumbar vertebrae had considerable osteoarthritis (OA), evidenced by the large osteophytes where L8 joined the sacrum (attached to the pelvis).

Isle Royale wolves
There are 319-321 bones in a dog, depending on the length of its tail. A wolf is probably similar. Some observers have thought male 183 had a rather short tail. Well, here it is, in its entirety.

Tragedy Was Part of M183′s Pack History

Years ago, there were up to 50 wolves in different packs on Isle Royale. For a time, they were quite effective at taking down the island’s big moose population. But a combination of inbreeding, accidents and disease caused the wolves’ numbers to dwindle to just M183 and F193. The closely-related pair were the only permanent wolves on the island for years before the new translocated wolves began arriving in the fall of 2018. By then, the moose population had been growing exponentially, and their overbrowsing of vegetation was a big concern to the park service. They needed to bring back the predator balance – big wolves from Canada, Minnesota and the U.P. that could kill moose and resurrect genetic diversity in the island’s pack system.

M183′s lineage was the whitish wolves of the Chippewa Harbor Pack. He was just a young wolf in 2011 when the pack was dealt a tragic blow. In December of that year, three members of that pack died when they fell down an old mine shaft on the island. They included the pack’s alpha male, another radio-collared male that was high-ranking, and a young pup. “M183 would have been alive and he would have seen all that,” Peterson said. “Wolves definitely are affected directly by the death of their packmates.”

Isle Royale wolves
This photo from 2010 shows a young wolf in the Chippewa Harbor Pack. Male 183 was born in 2008, in this pack, so this could be the first photo of him in his youth.

Because of his island history, researchers were excited to study M183′s genome. Michigan Tech described it like this: “With an esteemed heritage — his grandmother was known as the Cinderella Wolf and his great grandfather The Old Grey Guy, two important wolves within the Isle Royale family tree — the male’s genes carry the story of genetic rescue and severe inbreeding, phenomena that are hard to study in the wild.”

Information they glean from M183′s DNA will help them make wildlife management decisions in the future – both on Isle Royale and possibly with wolves elsewhere.

“The wolves of Isle Royale have been showing us for some time now how the life of an individual animal can affect an entire ecosystem,” John Vucetich, professor of ecology and another Winter Study co-lead, said earlier this year. “The Old Grey Guy, who came across an ice bridge and introduced new genes into the population, and Cinderella, a notable alpha who survived a pack coup, are important examples. And the recovery of this carcass from the last known male wolf of the previous population may well prove to be another important example.”

Isle Royale wolves
Isle Royale researchers described this rebuffed incest attempt this way: “We think this couple mated once, in 2014. The result wasn’t pretty … . I don’t think the female wanted any more of that.”

A Legacy of Wolf-Pack Territory

Peterson said M183′s legacy lives on in a way researchers didn’t initially anticipate. As the new wolves were released on the island beginning in 2018, the old island-born pair claimed the east end of Isle Royale for themselves. The new wolves were aware the older ones were there, Peterson said, so they were forced to set up their territories elsewhere. This pushed the first new groups to take over the west end of the island.

As soon as M183 was dead, radio-tracking collars and web cameras showed the new wolves began to crisscross the east end of the island. “They moved in right away and … basically took over that right away,” he said. “I was surprised to see that there was a holdover resulting from these last two wolves – essentially a legacy for the new population. They sorted themselves out on a template that the old wolves provided.”

As you might expect from the island’s scientists, there was not a lot of sentimentality wrapped up in M183s death. While a few of the researchers have used nicknames for some of the park’s wolves, the last island-born male didn’t have one, Peterson said. He’d always been just M183. And that’s good enough for the people who saw him the most – a number is just the same as a name, Peterson pointed out.

“It’s odd but I mostly deal with dead animals,” he said. “Once they are dead, they are just another sample for me. When they are alive, they have personalities and they all have individual stories. For me, it’s nice to know what all the information is.”

“Eleven years is a long, long time.”

Isle Royale wolves
Wolf M183’s body being bagged and prepped for transport off Isle Royale.
Isle Royale wolves
This is Male 183 inspecting tracks left by a fox.

via Isle Royale’s last native-born male wolf: The secrets his bones revealed | MLive