Mammoths roamed far and wide, possibly to their doom, study says

An illustration of an adult male woolly mammoth.

Courtesy of University of Alaska Fairbanks

During the last ice age, woolly mammoths were among the largest creatures to walk the North American landscape. Now, a team of American and Canadian researchers has discovered that the elephantine beasts took the “walking” part of their job description quite seriously.

Based on an analysis of a single tusk from an adult male woolly mammoth found in Alaska, the scientists determined that the animal journeyed about 70,000 kilometres over the course of its life – a trip equivalent to nearly twice around the world.

“The range is staggering. … He definitely moved across a huge, huge area,” said Clement Bataille, an assistant professor of earth and environmental science at the University of Ottawa and a co-author on the study.

Dr. Bataille said the high degree of mobility may have been part of the mammoth’s mating strategy. In comparison, African elephants can travel a lot, too, he added, and males typically depart from the groups they are born into once they reach sexual maturity.

However, Dr. Bataille and his colleagues note that the requirement for such a large range to roam in may have ultimately hastened the extinction of the species once the climate warmed and the shaggy grazers were hemmed in by shifting vegetation patterns. That, in turn, would have left them more vulnerable to predators, including human hunters.

The study began in 2018 when Matthew Wooller, director of the Stable Isotope Facility at the University of Alaska Fairbanks, invited Dr. Bataille and other colleagues to join an effort to extract information from a mammoth fossil discovered in 2010 on the north side of the Brooks mountain range, a few hundred kilometres from the Arctic Ocean. The fossil dates back 17,000 years, to a time when much of Alaska was a glacier-free grass plain connected to Siberia by the Bering land bridge.

Mat Wooller, director of the Alaska Stable Isotope Facility, kneels among a collection of some of the mammoth tusks at the University of Alaska Museum of the North.

JR Ancheta/Courtesy of University of Alaska Fairbanks

The researchers nicknamed their specimen “Kik,” after a river system near the place where it was found.

Using the mammoth’s sliced-open tusk, they obtained detailed measurements of oxygen and strontium isotopes that were locked in the ivory material. The mammoth acquired the isotopes, which vary according to local geology, through the vegetation and water it consumed over the course of its life. As the tusks grew at the rate of about five to six centimetres each year, they recorded changes in isotope levels, which reveal when and how often the animal moved between locations with different geology.

The team also tested isotope levels in rodents that were gathered in different parts of Alaska as part of museum collections. That allowed them to match their mammoth isotope measurements to geographic locations. Finally, they used artificial intelligence software to reconstruct possible paths the mammoth may have taken, working backward from the location where it died at the age of 28.

The results suggest that Kik began its life in the Yukon River basin of central Alaska. As a juvenile it moved regularly in a north-south pattern, during a time when it was likely part of a herd, the researchers said. At about age 16 its movements transitioned to longer distance travel, often centred on certain core areas where it stayed for periods of time before setting out for new pastures.

“It just takes off and goes on these 500- to 600-kilometre trips all at one time, going from one core area to the next,” Dr. Bataille said. The study found that some of the places where the mammoth lingered are frequented today by migrating herds of caribou.

Jeffrey Rasic, a study co-author and archaeologist with the U.S. National Parks Service based in Fairbanks, said the data suggest that Kik followed a predictable sequence of movements. If that was typical for Alaskan mammoths, it would have provided a huge incentive for hunters moving into the area from Asia to situate themselves in places where they could reliably expect to meet their quarry at certain times of the year, rather than pursuing them over a vast landscape.

“That would be an ideal set-up for intercepting a really big ticket meal item like a mammoth,” he said.

Vincent Lynch, an evolutionary biologist at the University at Buffalo who was not involved in the study, said that while it’s not surprising to find animals moving over great distances, it’s quite a different matter to show that it happened in a species that no longer exists.

“That’s the trick that makes this study interesting,” he said. “It helps us better reconstruct the behaviour and ecology of mammoths in a way that’s really remarkable for an extinct species.”

Dr. Lynch, who has studied the genetics of the last known population of woolly mammoths, which died out about 4,000 years ago, said it’s an open question whether large-scale movement was a disadvantage.

“We tend to think that widely distributed species which are mobile … might be better able to find new habitats should the environment change. But could mammoths find refuge in a world that was warming?” he said.

One obvious limitation of the study is that its conclusions depend entirely on the movements of a single individual. Dr. Bataille said that he and his colleagues plan to perform a similar analysis on a female mammoth specimen for comparison.

The team’s study was published Thursday in the journal Science.

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