The Surprising Reason Female Caribou Grow Antlers

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A A large antler rack is a status symbol that we expect from a mature male deer or elk. Because rival males lock their antlers in a shoving competition against their partners, the bigger the better. But females are generally antlerless (developing at most short, unbranched nodes), with the exception of caribou, in which females sport modest supports. A recent study published in Ecology and evolution discovered a surprising behavior that could explain why female caribou have such antlers.

The researchers analyzed caribou antlers and skeletal bones from caribou, moose and muskox collected from the coastal plain of the Arctic National Wildlife Refuge in Alaska. The region serves as an important calving ground for the “porcupine herd,” a group of caribou known for their long annual migrations. After female caribou travel up to 1,200 miles north to give birth, they shed their antlers, usually just a day or two after giving birth.

The study found that about 86 percent of the 1,567 antlers lost showed signs of gnawing and that almost all of the gnawing (judging by tooth marks) came from caribou. In contrast, only about 44 percent of the skeleton’s bones were gnawed away, mostly by carnivores such as foxes and wolves, and only 4 percent by rodents. Rodents leave parallel marks on their pair of enlarged front teeth, while carnivores leave distinct canine puncture holes.

Read more: “What deer tell us”

“We knew animals were gnawing on these antlers, but everyone thought they were mostly rodents. Now we know they’re actually caribou. My jaw dropped when our results started to become clear,” study author and University of Cincinnati paleoecologist Joshua Miller said in a news release.

Given the location of the antlers on the calving grounds, the researchers deduced that it was female caribou who were chewing them. Although it was impossible to distinguish the repeated gnawing of an individual mother from the tooth marks of multiple mothers, the extent of the gnawing implied that the caribou regularly consumed the shed antlers. The timing of antler gnawing at calving suggests that females use their antlers, either their own or those lost by others, to supplement their diet with essential minerals.

During their gestational migrations, female caribou likely become depleted of essential minerals, such as calcium and phosphorus, but must be prepared to nurse their young and fortify themselves for the coming winter. By shedding their antlers at birthing sites, females ensure a future supply of essential minerals.

“They are altering this habitat, seeding the landscape with these extremely important minerals that animals may have difficulty getting enough of,” explained the study’s lead author, doctoral student Madison Gaetano, adding that “caribou literally bring tons of phosphorus to their calving grounds every year.”

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Main image: David Turko / Shutterstock

• Devin Reese

  Published on March 2, 2026

  Devin Reese is the editor-in-chief of Natural history and a science writer based in Alexandria, Virginia.