What determines the color of an animal’s antlers? Elk, deer, moose, caribou and other antlered mammals exhibit various colors on their headgear. Some are quite light, while others are dark brown. Is the color a genetic trait or does it stem from some other factor, such as the animal’s diet?

No matter the species, antlers are white, just like other bones. When the velvet (the tissue that supplies blood to growing antlers) dries and peels away in late summer, an animal’s antlers are pure white and uncolored. Just last week, my family and I spotted a large bull elk in Yellowstone National Park. The velvet hung in tatters from the bone-white rack on his head.

So where does the color of antlers come from? Males of antlered mammal species aggressively rub their antlers on trees and shrubs. As they do so, their antlers are stained by the bark. The color of an animal’s antlers is determined by what he’s been rubbing them on and for how long. For example, many elk rub their antlers on lodgepole pines. Their antlers not only pick up color from the bark, but also become covered with pitch. When the elk then gores the dirt or rubs on other trees, the antlers pick up even more color, giving them an overall brownish appearance.