Bighorn sheep are named for the large, curved horns borne by the rams (males). Ewes (females) also have horns, but they are shorter with less curvature. They range in color from light brown to grayish or dark, chocolate brown, with a white rump and lining on the backs of all four legs. Male bighorn sheep have large horn cores, enlarged cornual and frontal sinuses, and internal bony septa. These adaptations serve to protect the brain by absorbing the impact of clashes. Bighorn sheep have preorbital glands on the anterior corner of each eye, inguinal glands in the groin, and pedal glands on each foot. Secretions from these glands may support dominance behaviors.
Bighorns from the Rocky Mountains are relatively large, with males that occasionally exceed 230 kg and females that exceed 90 kg.
In contrast, Sierra Nevada bighorn males weigh up to only 90 kg and females to 60 kg. Males' horns can weigh up to 14 kg, as much as the rest of the bones in the male's body.
Size: Males typically weigh 58–143 kg, are 91–104 cm tall at the shoulder, and 180–200 cm long from the nose to the tail. Females are typically 34–85 kg, 76–91 cm tall and 140–170 cm long.
Life-span: rams is typically 9–12 years, and 10–14 years for ewes
Food: herbivorous, feeds during the day constantly grazing, reeds, branches and leaves of trees, bushes and seeds. Before swallowing food for final digestion, regurgitate to chew.