Why do female caribou have antlers? They eat them

In a paper published in the journal Ecology and Evolution, UC College of Arts and Sciences Associate Professor Joshua Miller and doctoral graduate Madison Gaetano theorize that it's because the animals, females in particular, derive important nutrition from shed antlers when and where they need it most — their calving grounds.

An analysis of antlers and bones collected in the Arctic National Wildlife Refuge, where caribou in enormous numbers migrate each year, found that caribou gnaw on antlers shed years earlier to supplement their diets with minerals like calcium and phosphorous.

Researchers discovered that a vast majority of antlers collected in the Arctic for the study had telltale gnaw marks left behind by caribou. The area of the study is a historic calving ground for the Porcupine caribou herd, which makes an epic 1,500-mile migration each year.

Antlers and bones take decades or centuries to decompose in the cold, arid landscape of the Arctic. Since female caribou shed antlers around the time of year they give birth, they have a ready source of minerals to draw upon to support them and their newborns.

UC researchers discovered that caribou ignore the bones but regularly eat antlers starting at the tips of their slender tines.

“[Caribou] are just really going after the antlers. They are highly selective,” Miller told Scientific American.

Scientists know that rodents and other animals gnaw on bones and antlers. But UC researchers determined that the primary culprit gnawing on caribou antlers in the Arctic are other caribou.

The study found that 86% of the 1,567 antlers they examined showed signs of gnawing and 99% of the gnaw marks were left by caribou. Researchers observed marks from rodent teeth on less than 4% of gnawed antlers. And they found evidence of carnivore gnaw marks on bones collected for the study but not antlers.

Read the Scientific American story.

Featured image at top: UC Associate Professor Joshua Miller, left, U.S. Fish and Wildlife Service employee Maria Berkeland and UC doctoral graduate Madison Gaetano conduct research on caribou in the Arctic National Wildlife Refuge. Photo/Provided