Bighorn Sheep

NPS Photo

While commonly associated with mountain ranges of Western America, bighorn sheep (Ovis canadensis) also inhabit rugged areas of the Midwest, such as North Dakota’s Badlands. Extirpated from the area by the early 1900s due to overhunting and disease introduced by domestic livestock, this iconic species was absent from the area until reintroduction efforts began in 1956. Since then, population levels have rebounded to approximately 490 animals, making them the rarest ungulate in the state to encounter. These unique animals can be found throughout the Badlands in sheer terrain near the Little Missouri River and in the North Unit of Theodore Roosevelt National Park.

Bighorn sheep are large, herbivorous mammals that are well adapted to life in environments with steep terrain. Their hooves are specialized for climbing, with a hard outer edge and a soft, concave underside, providing excellent traction. This adaption allows them to utilize steep terrain to escape predators and traverse areas not easily accessed by other species. Females, also known as “ewes”, capitalize on this ability and give birth to their young in steep areas to keep them safe and inaccessible.

Among their many unique features, this species is primarily characterized by their impressive horns, which are more prominent in males. These horns can grow in a spiral shape and weigh up to 30 pounds in older males, also known as “rams.” The horns of rams are used for dominance displays and in head-to-head combat with rival males during the mating season, known as “the rut.” Females have smaller horns with a subtle curve. Bighorn sheep have a grayish-brown coat made of dense, woolly underfur covered by longer guard hairs, which helps insulate them from cold temperatures. They also have excellent eyesight and a keen sense of smell, which help them detect predators, such as coyotes and mountain lions.

Like many other ungulates, bighorn sheep herds expand and contract throughout the year depending on the season. For most of the year, older rams are solitary and will be found alone or in small groups with other males known as “bachelor groups.” During the spring and summer, ewes will join one another and form “nursery bands,” comprised of their lambs and yearling offspring. When fall arrives and the rut begins, rams will join ewe groups and compete for mating opportunities. Afterwards, ram groups split off from ewes for the winter and the social cycle repeats next year.

A species unlike any other in the region, it’s no wonder why so much effort and resources have been focused on restoring populations in the Badlands. If you’re hoping to see one while visiting the park, you’ll need to focus your efforts in the North Unit. Terrain in the South Unit is not steep enough for suitable sheep habitat and none have been observed there for years.