Ancient Squirrels Feasted on Meat From Carcasses of Mammoths, Bison, and Even Big Cats

These squirrels had no quarrels about what they were eating.

Ancient poop revealed the surprisingly carnivorous nature of an Arctic survivor.

Bits of this poop, belonging to Arctic squirrels, had sat locked in Yukon permafrost for tens of thousands of years — and in one case, close to 700,000 years. When scientists analyzed the molecular contents, they found something that doesn’t fit with the idea of the cuddly, plant-eating ground squirrel. They found traces of hares, lemmings, birds, horses, bison, mammoths, and even predators.

Turns out, when dealing with hibernation hunger, meat was very much on the menu for these guys.

Blood on Its Whiskers

Modern Arctic ground squirrels are often described as plant-eaters, and for the most part, that’s what they are. They eat grasses, sedges, flowers, leaves, buds, seeds, fungi. But they’re opportunistic feeders. They’ll eat everything from flowers and mushrooms to insects and even carrion. Turns out, their ancestors did the same.

There are 13 species in the genus Urocitellus of ground squirrels, most of them living in North America, with one lineage extending into Siberia. They evolved as cold-country specialists, shaped by open steppe and tundra habitats and the brutal demands of hibernation, because all these squirrels hibernate.

The Arctic ground squirrel is the extreme case: it can hibernate for much of the year, with body temperature dropping below freezing. They can go as cold as −2.9°C, or 26.8°F, without their tissues freezing. To achieve this stunning feat, however, they need to fatten up before hibernation.

They’re also very hungry when they emerge from hibernation. “They’re desperate for protein and high-quality diet items”, says Bryan McLean, an evolutionary biologist at the University of North Carolina at Greensboro, for Nature. “I’ve seen them eating roadkill individuals of the same species.”

 Tyler Murchie, a study co-author and McMaster University biomolecular archaeologist, told Popular Science these squirrels sometimes act “like tiny Arctic pack rats.”

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So when researchers opened the molecular record inside ancient Yukon coprolites, they were not looking at some bizarre extinct behavior. They were seeing an old version of a strategy that still exists today.

The Mammoth Steppe, Reconstructed from Squirrel Poop

Feces are unusually intimate archives. A bone tells you about the animal whose skeleton it built, but feces can tell you about a meal, a microbiome, and the ecosystem all at once.

Ground squirrel burrows are especially interesting for that reason. The animals dig underground homes and use latrine areas. In permafrost, some of those burrow systems freeze and stay sealed. The Yukon sites in this study included samples from several periods: about 17,000 years ago, 30,000 years ago, 80,000 years ago, and one extraordinary sample from around 700,000 years ago.

The scientists used two main DNA approaches to analyze them. First, shotgun metagenomics, which broadly sequences whatever DNA fragments are present. Second, targeted enrichment, which uses molecular probes to pull out desired ancient DNA fragments from the chaos. And that chaos is very real, as feces can contain compounds that can interfere with the enzymes needed for DNA analysis. The team had to tune the extraction process, including reducing the amount of raw sample, before the ancient molecules could be read cleanly.

The plant DNA shows squirrels ate everything they could get their whiskers on: grasses, sedges, plantain, sagebrush relatives, willow, buttercups, alpine sweetvetch, and other tough tundra-steppe plants. The menu matches the mammoth steppe — the cold, dry, open ecosystem that once supported mammoths, horses, bison, birds, rodents, and hardy low-growing plants. In other words, the squirrels were eating what the landscape offered, and their feces preserved that landscape in miniature.

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Then comes the meatier part. The animal DNA in the pellets includes signals from rodents, hares, birds, mammoth, horse, bison, canids, and ground squirrels themselves. This doesn’t necessarily mean a squirrel took a bite of that animal. Some DNA could come from nest-raiding or insects. But it suggests that when it came to meat, squirrels were also eating pretty much everything they could find.

Squirrels and Meat

Surprisingly, this doesn’t make ancient squirrels feel like oddballs. Rather, it shows that they were more like ancestors with a familiar playbook.

Modern ground squirrels, too, can turn carnivorous when opportunity knocks. In fact, recent observations of meat-eating squirrels have forced scientists to rethink squirrels altogether. This new study suggests this may be a glimpse of a much older survival strategy.

So, as strange as it sounds, these ancient squirrels weren’t freaks. They were flexible survivors, taking calories wherever they could find them, especially around hibernation. The Yukon coprolites show that this opportunistic appetite has deep roots — and that sometimes, even a mostly plant-eating squirrel needs meat to make it through the cold.

For hundreds of thousands of years, ground squirrels tunneled, cached, slept, and left behind waste. Permafrost did the rest. Now, those pellets are letting scientists read a vanished world from the bottom up.

The study was published in Nature Communications.