Research sheds light on why they are only species of deer in which females have antlers

Caribou, also called reindeer, are the only species of deer in which females have antlers.

Researchers previously theorised that females could be using their antlers to defend against predators or show dominance at feeding sites.

The new study reveals that the females rely on their calcium-rich antlers as a “mineral reservoir” after the 1,500-mile round-trip migration.

In caribou, bony antlers grow from the top of the skull and stretch up to 4ft and weigh as much as 10kg each in males. Female antlers are much smaller.

Antlers provided a ready source of minerals including calcium and phosphorus

The study documented antlers shed by caribou in the Arctic tundra that had stayed undisturbed for decades.

Researchers found that these antlers provided a ready source of minerals including calcium and phosphorus at a key time in their migration. Their analysis revealed that most of these antlers had been chewed on.

Further examination of the teeth marks revealed the caribou themselves as the prime culprits.

Some 86pc of the 1,567 antlers examined in the study showed signs of gnawing, and almost all the gnaw marks were left by caribou.

“We knew that animals gnawed on these antlers, but everyone assumed they were mostly rodents. Now we know it’s really caribou,” said Joshua Miller, an author of the study published in the journal Ecology and Evolution.

“My jaw dropped when our results started to become clear,” added Dr Miller, a biologist at the University of Cincinnati in the US.

Minerals from the antlers also return to the soil and help support the growth of grasses and lichens

Female caribou shed their antlers within days of giving birth, making them available as a nutritional supplement when they return to the site.

“These antlers last for centuries or longer in the Arctic and they are a source of nutrients that get revisited again and again,” Dr Miller said.

Minerals from the antlers also return to the soil and help support the growth of grasses and lichens the caribou eat.

“They are engineering this habitat, seeding the landscape with these super-important minerals that can be quite hard for animals to get enough of,” Dr Miller said.

“Phosphorus, in particular, is very important for new mothers trying to produce high-quality milk for feeding their young.”