JACKSON, Wyo. — Yellowstone National Park (YNP) shared on Thursday, Nov. 21, that bighorn sheep can be seen with their horns year-round.

While animals with antlers, like elk, deer and moose, shed their antlers around springtime, animals with horns, like bighorns and bison, hold onto their horns until death. Even if horns chip, crack or break due to heavy use, they will still remain attached to the skull.

“Long story short, if you see a horn without its owner, it’s curtains for that unlucky ungulate,” YNP wrote in a Facebook post last week.

According to the National Park Service (NPS), bighorn sheep horns are composed of keratin, the same material that makes up human fingernails. As a potential suitor in competition with other males, a male bighorns or rams will develop heavy horns that curl with age in order to demonstrate physical prowess to females or ewes. 

Research also shows, however, that male bighorns that survive exposure to pneumonia outbreaks can actually experience severely stunted horn growth.

Bighorn sheep are also notable for their unique rectangular pupils, an evolutionary advantage against their predators. Read more about this here.

In Grand Teton National Park, visitors are encouraged to report any sightings of bighorn sheep or mountain goats to a GTNP ranger or by filling out a Rare Animal Sighting form at any of the park’s visitor centers. Wildlife watchers can also contact Sarah Dewey at sarah_dewey@nps.gov with those sightings.

River Stingray is a news reporter with a passion for wildlife, history and local lenses. She holds a Master's degree in environmental archaeology from the University of Cambridge and is also a published poet, dog mom and outdoor enthusiast.