Gray wolves don’t just change where they roam when the climate shifts. New research suggests they also change how they eat.
In warmer periods, wolves appear to consume harder parts of carcasses, including bones, as if they’re squeezing every last bit of nutrition out of a meal when conditions make hunting and feeding more difficult.
The study was led by the University of Bristol with the Natural History Museum.
The researchers compared wolf teeth from two ancient warm intervals and from modern wolves in Poland, where winters are getting milder and snow cover is shrinking.
Their goal was to see whether warming climates leave a clear signature in wolf diets and whether that signature is already showing up today.
Reading a wolf’s diet in its teeth
The team used a technique called Dental Microwear Texture Analysis (DMTA). When an animal chews, microscopic scratches and pits form on the tooth surface.
Those tiny marks can reflect what the animal was eating in the final weeks or months of its life – sometimes called the “last supper” effect.
To test how diet changed with climate, the researchers examined gray wolf molars from three time periods.
One set came from around 200,000 years ago, when summers were similar to today but winters were colder. Another set came from around 125,000 years ago, a warmer interglacial period with hotter summers and milder winters.
The final set came from modern wolves in Poland, a region where warming winters and reduced snow cover are already being observed.
The question was simple: do warmer conditions correlate with wolves eating tougher, harder food?
Fossils show a clear diet shift
When the team compared the fossils, they found the two warm periods didn’t look the same in terms of diet.
The tooth marks suggested wolves in the younger interglacial ate harder material than wolves in the older one.
“The DMTA results from fossil wolves from the two interglacial periods were very different,” explained study co-author Danielle Schreve from University of Bristol.
“Tooth surface features indicate that the dietary behavior of wolves from the older interglacial included the consumption of less hard food than those from the younger interglacial period.”
“Wolves during these warmer temperatures appear to have been consuming carcasses more completely.”
“The real surprise was that modern wolves from Poland, where climate warming is also ongoing, show the same patterns as those from the younger interglacial, highlighting that they are also experiencing hitherto hidden ecological stress,” Schreve said.
Thus, wolves can still be present, still reproducing, still hunting – and yet their teeth may be quietly recording that they’re under pressure, working harder to feed themselves.
When wolves start crunching bones
Across the data, the pattern was consistent. Wolves living in warmer climates consumed harder foods, including bones. The researchers describe this bone-eating behavior as durophagy.
“The findings suggest wolves were working harder to extract nutrition during warmer climate periods, scavenging more extensively or consuming parts of prey they would normally avoid,” said study lead author Amanda Burtt from Bristol.
“The findings have major implications for wolf conservation across Europe and beyond. Gray wolves are often assumed to be resilient to climate change, but this research shows that warming temperatures should be considered a significant factor in conservation planning.”
That’s a direct challenge to a common assumption. Wolves are famously adaptable, and in many places they’ve rebounded. But adaptability doesn’t always mean “unaffected.” Sometimes it means “coping,” and coping can come with costs.
Wolves during snowier winters
One reason warming matters so much is that wolves tend to thrive in cold, snowy winters. Deep snow can make herbivore prey more vulnerable by limiting access to food and making escape harder.
Wolves also move efficiently on snow and ice. Cold conditions are linked with heavier wolves and higher pup survival.
When winters get warmer and snow cover declines, that whole dynamic shifts. Prey animals can move more easily. Hunting becomes harder.
Wolves may need to spend more energy to get the same payoff, and when they do get a kill, they may need to use it more thoroughly – which fits the tooth-wear evidence of heavier bone consumption.
Put bluntly, a wolf built for winter is being nudged into a less wolf-friendly world.
A strange twist
The study also points out something slightly uncomfortable. In Poland, wolves can offset some climate-related stress by hunting deer and wild boar near farmland, and by scavenging roadkill.
That’s not exactly a conservation dream scenario, but it may provide calories when natural hunting becomes more costly.
Ironically, wolves farther from human-modified landscapes could face bigger challenges in the future because they have fewer alternative food sources to fall back on.
In a warming world, the “wildest” places may not automatically be the easiest places for wolves to thrive, especially if prey becomes harder to catch without the advantage of snow.
Fossil collections and modern conservation
One of the coolest parts of this study is how it uses museum fossils not as dusty relics, but as a climate-and-ecology archive.
Study co-author Neil Adams, curator of fossil mammals at the Natural History Museum in London, emphasized how long some of these specimens have been waiting for a question like this.
“The fossil wolf teeth involved in this project include some that have been part of the national collection for over 175 years.”
“Amid the current biodiversity and climate crises, it is more important than ever that fossil specimens in museum collections are leveraged to their full potential in studies like ours focused on conservation palaeobiology.”
“This emerging field seeks to apply knowledge from the fossil record to modern issues of nature conservation and restoration.”
What this means for wolf conservation
The researchers’ bottom line is not that wolves are doomed. It’s that climate change should be treated as a real pressure on large carnivores, even ones we consider tough and flexible.
If warming winters force wolves into more energetically expensive hunting and riskier feeding strategies, that can influence health, reproduction, and long-term population stability – especially in places where human food sources aren’t available or where landscapes are fragmented.
The study argues that long-term conservation planning needs to include climate, not just habitat and human conflict.
Because sometimes the warning signs aren’t dramatic population crashes. Sometimes they’re microscopic scratches on a molar saying: life is getting harder, and we’re chewing the bones to prove it.
The study is published in the journal Ecology Letters.
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