Why do female caribou have antlers unlike other female deer?
What makes female caribou so special? Watch this video for more details. Image via Ronan Hello/ Unsplash.
For decades, biologists have debated the purpose of antlers in female caribou. Males in many deer species grow antlers to compete for mates, but only in the caribou species do we see females with antlers. On February 24, 2026, a new study said these antlers serve as a crucial source of nutrition, especially for mothers with newborn calves.
Each year, pregnant females complete an epic migration to their Arctic calving grounds, give birth, and then shed their antlers within days. On the windswept tundra, where nutrients remain scarce and survival demands efficiency, those discarded antlers may hold the key to a long-standing evolutionary mystery.
Researchers from the University of Cincinnati led the study in the Arctic National Wildlife Refuge and published their findings on February 24, 2026, in the peer-reviewed journal Ecology and Evolution.
Female caribou antlers and diet
Biologists have long puzzled over why female caribou – unlike other female deer – grow antlers. The new study points to nutrition as a key reason.
Researchers examined 1,567 shed antlers from Arctic calving grounds, where migratory females give birth and drop their antlers each year. They found that 86% showed signs of gnawing. Of those marks, 99% came from caribou.
Joshua Miller of the University of Cincinnati described the moment the pattern emerged:
We knew that animals gnawed on these antlers, but everyone assumed they were mostly rodents. Now we know it’s really caribou. My jaw dropped when our results started to become clear.
The findings suggest that mothers, especially those with newborn calves, chew antlers shed years earlier to replenish minerals such as calcium and phosphorus.
Female caribou antlers and calving season
Female caribou migrate hundreds of miles to reach calving grounds. This includes the Porcupine herd, famous for its 1,500-mile (2,400-km) round-trip journey. Within days of giving birth, females drop their antlers in the very place where they need nutrients most.
In the Arctic’s cold, dry tundra, shed antlers can sit undisturbed for centuries. That durability turns old antlers into long-term mineral stores. Over time, the minerals gradually return to the soil, enriching it and supporting the sedges, grasses and lichens that caribou feed on. Miller said:
These antlers last for centuries or longer and they are a source of nutrients that get revisited again and again. Given the results of our study, this is probably an important clue to a way that antlers benefit female caribou that has gone underappreciated.
Phosphorus plays a critical role for new mothers producing milk. Miller noted that caribou transport tons of phosphorus to calving grounds each year through their antlers:
They’re engineering this habitat, seeding the landscape with these super-important minerals that can be quite hard for animals to get enough of. Phosphorus in particular is very important for new mothers trying to produce high-quality milk for feeding their young. Caribou bring literally tons of phosphorus to the caribou calving grounds every year.
Tooth marks tell the story
To determine which animals chewed the antlers, researchers analyzed bite patterns in Miller’s lab. Carnivores such as bears and wolves leave distinct damage that differs from the marks made by rodents or caribou.
The results drew a sharp line between antlers and skeletal bones. Most of the 1,567 antlers examined showed signs of chewing. When researchers identified the tooth marks, they found that caribou left 99% of them. Rodents accounted for the rest, and researchers found no evidence that predators chewed the antlers at all.
Bones told a different story. The team also examined 224 skeletal bones from caribou, moose and musk ox collected in the same region. Unlike the antlers, many of the gnaw marks on these bones came from predators such as wolves and bears. Caribou accounted for about 12% of bone gnawing, while rodents made up just 1%.
The contrast makes the pattern clear; predators target skeletal remains, but caribou chew shed antlers.
And in case you were wondering why females don’t chew males’ much larger antlers, it’s because males shed them months earlier and far from the calving grounds. Females rely on the antlers they’ve carried with them to get the minerals they need during the critical weeks after giving birth.
Female caribou antlers and defense
Scientists have often argued that females use antlers to secure better grazing spots or fend off predators. But Madison Gaetano of the University of Cincinnati questioned that assumption. She said:
I think it’s reasonable to question how helpful they would be in fighting off a predator.
Gaetano noted that females rely more on hooves to trample or kick threats. She also pointed out that females shed their antlers just as they give birth.
Female caribou shed their antlers right around when they give birth. That means they are antlerless when it would be most crucial to have antlers to defend a young calf if they were a defense mechanism.
Also, Miller said many plant-eating mammals seek minerals in unexpected ways. He commented:
It is fairly ubiquitous. I’ll never forget watching a kangaroo eat a dead bird in Australia. Herbivores look for nutrients in all kinds of interesting ways.
Bottom line: A new study says female caribou chew shed antlers to gain vital minerals, supporting their calves and enriching Arctic tundra ecosystems.
Source: A Gnawing Question: How Do Caribou and Other Arctic Mammals Exploit Shared Bone Resources?
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