What Do Wolves’ Broken Teeth Reveal?

Analysis by Dr. Karen Shaw Becker

gray wolf

Story at-a-glance -

  • The skulls and teeth of several large, meat-eating animals, from the present to over thousands of years ago, have been examined by scientists to reveal many interesting facts about how they survived
  • Scientists say there’s a strong association between more broken teeth in wolf skulls and a lesser amount of food available to them
  • Adult wolf skulls used in the studies came from the Lake Superior region, Scandinavia, and from wolves that died between 1874 and 1952 collected from Alaska, Texas, New Mexico, Idaho and Canada
  • Large carnivores like wolves have had to work harder at catching prey when there were fewer to be found, but it was also found that more of the prey was eaten down to the bone
  • Scandinavian wolves were able to find prey more quickly because they were more plentiful, so they not only moved on before finishing the entire carcass, they also went away with fewer broken teeth

Animals that rely on a carnivorous diet also count on something else crucial to survival: their teeth. Blaire Van Valkenburgh, an ecology professor and evolutionary biologist at UCLA, has found that the skulls – and teeth in particular – of lions, tigers and wolves that roamed the wild 50,000 years ago are particularly fascinating because of what they reveal about their lives as carnivores.

Van Valkenburgh spent three decades poring over the skulls belonging to these and other large, meat-eating animals. One thing she noted in her study, published in eLife Sciences,1 was in regard to the large number of carnivores with broken teeth, which begged the question of how they were able to survive with a limited amount of prey.

The bulk of her research centered on adult-sized skulls belonging to gray wolves. According to Science Daily, 160 of them were from the Yellowstone Heritage and Research Center in Montana, and more besides:

“(Sixty-four) adult wolf skulls from Isle Royale National Park in Lake Superior that are housed at Michigan Technological University; and 94 skulls from Scandinavia, collected between 1998 and 2010, housed in the Swedish Royal Museum of Natural History in Stockholm. She compared these with the skulls of 223 wolves that died between 1874 and 1952, from Alaska, Texas, New Mexico, Idaho and Canada.”2

There were no wolves in Yellowstone for a period between the 1920s and up to 1995, when 31 of the gray wolf species from British Columbia were introduced. Since that time, about 100 of them have lived in the national park. About 90% of the prey that gray wolves pursue are elk, but the elk population has diminished dramatically since the gray wolf reintroduction. The ratio was 600-to-1 in the beginning, while it’s closer to 100-to-1 more recently.

The Correlation Between Broken Wolf Teeth and Available Prey

From the wolf skulls she’s studied, Van Valkenburgh said she found a strong association between more broken teeth in the wolf skulls and a lesser amount of food available to them. In essence, large carnivores like wolves have had to work harder at catching prey when there were fewer to be found, but she also found that more of the prey was eaten down to the bone.

“Broken teeth cannot heal, so most of the time, carnivores are not going to chew on bones and risk breaking their teeth unless they have to,” she observed. She added that wolves didn’t break their teeth in the first 10 years after returning to Yellowstone, and they also didn’t eat all the elk. However, that changed in the following decade:

“As the number of elk declined, the wolves ate more of the elk's body, and the number of broken teeth doubled, including the larger teeth wolves use when hunting and chewing.

The pattern was similar in the island park of Isle Royale [near Lake Superior]. There, the wolves' prey are primarily adult moose, but moose numbers are low and their large size makes them difficult to capture and kill. Isle Royale wolves had high frequencies of broken and heavily worn teeth, reflecting the fact that they consumed about 90% of the bodies of the moose they killed.”3

Scandinavian wolves, which also eat mostly moose, proved to exhibit a different scenario, Van Valkenburgh explained. There, the moose-to-wolf ratio is around 500-to-1, but only 55-to-1 in Isle Royale. That’s consistent with Van Valkenburgh’s theory; the wolves in Scandinavia ate about 70% less of the moose they killed in comparison with the wolves in Isle Royale.

In essence, because the Scandinavian wolves in her study were able to find their much more plentiful prey more quickly, they not only moved on before finishing the entire carcass, including the bones, they also went away with fewer broken teeth.

What Do Wolves Have in Common With Other Large Carnivores?

The scientist’s conjecture is that the same would be true of other large carnivores, including lions and bears. That includes the equivalent of those animals from the Pleistocene epoch from tens of thousands of years ago, such as dire wolves and saber-toothed cats, which she found to have far higher rates of broken teeth compared to modern carnivores.

In fact, according to another study of Van Valkenburgh’s in 1993, animals at the La Brea Tar Pits in what is now known as Los Angeles (and “the only active urban paleontological excavation site”4 in the U.S.) were as much as four times more likely to have broken teeth.

Part of Van Valkenburgh’s findings have led her and several colleagues to conclude that during those formative Pleistocene years, the attacks of large carnivores, in many cases much larger than their modern counterparts, were pivotal in the way ecosystems emerged in subsequent epochs. She concluded:

“We want to understand the factors that increase mortality in large carnivores that, in many cases, are near extinction. Getting good information on that is difficult. Studying tooth fracture is one way to do so, and can reveal changing levels of food stress in big carnivores.”5

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