To Antler or Horn: that is the question

Text and photos by Heather Cline 

Mountain Goat

There are many creatures in the animal kingdom that possess unique attributes, such as bold colors, patterns, and body shape. These qualities set them apart from other animals and serve different purposes such as camouflage or attracting a mate. Then you have those protrusions that emerge from the heads of ungulates, which are referred to as antlers or horns - but which is which? This post covers the differences between these bony protuberances and what purpose they serve their owners. 

The primary differences between antlers and horns come down to composition, growth, gender and shape. 

Antlers

Antlers are possessed by a much smaller group of individuals than horns, with just 4 species in North America: Deer, Moose, Elk, and Caribou. Unlike horns, antlers are branched with points.

Black Tail Deer in winter before antlers are shed

The composition of antlers are made up of bone-like structures that grow each year on male ungulates. They are made of bone, cartilage, nerves, blood vessels, fibrous tissue, and skin. All antlered animals go through a phase when the immature antlers are covered with fine hair called velvet. The velvet phase facilitates the growth of the antlers by providing a blood supply to the growing bone. Deer antlers have been known to grow as much as a quarter inch in a day, making the velvet the fastest growing animal tissue known in the world!

A young moose in summer where velvet is still covering antlers

Antlers drop annually in late winter, typically January through March. The process of dropping antlers does not hurt the buck. After a deer's antlers fall off, or shed, in mid-winter, they become tasty snacks for critters like mice and squirrels, who chew on them for the minerals. From spring through summer, the antlers grow back and are usually bigger than the previous year. As growth stops, the velvet covering the antler is lost and antlers are ‘polished’ in preparation for the mating season.

A group of Roosevelt Elk showing off their racks

Antlers are found only on male species with exception of the caribou which is shared by females as well. 

Although antlers continue to grow in size and increase in 'points' as they age, they are not a reliable gauge of the animal's specific age. Biologists refer to their teeth to estimate age instead. 

Horns

A much larger group of animals possess horns, and these exist all over the world. The animals displayed on this page are just a tiny sample of species that grow horns. 

Bighorn sheep; both males and females have horns, but the males are larger and more curled

Differences between horns and antlers include how they form. Horns are made of keratin and are covered by a sheath of hair follicles. While antlers grow from the ends or tips, horns grow from the base. Horns also grow continuously throughout the animal's life and are not shed annually. Finally, while antler bearing species are typically isolated to males, both male and females possess horns. 

Bison

Similar to antler, horns are used for social dominance, to protect one's territory and guard against predators. 

Impala

Pronghorns, which inhabit the western half of the United States and into Canada and Mexico, are an exception among horned species because they shed their horns annually. 

Pronghorn

So there you have it, the difference between antlers and horns. If this ever comes up in a game of trivia, you will be ready with the knowledge to nail the question. For more images of wildlife with horns, check out my gallery here.