These young mountain goats (Oreamnos americanus), also known as the Rocky Mountain Goats, are resting on their way up a steep slope in the Colorado Rocky Mountains. Mountain goats are sure-footed cliff climbers that are endemic to subalpine to alpine areas of North America. They are the largest mammal in these high-altitude environments often exceeding 3,900 meters (13,000 ft). In summer, they generally stay above tree line, but occasionally migrate to lower elevations in the winter. Despite its common name, they are not a member of Capra, the genus that includes all other goats, but rather related to antelopes, gazelles, and cattle.
Mountain goats are about 1 m (3.3 ft) tall at the shoulder and males are larger than females. Mountain goats can weigh between 45 and 140 kg (99 and 309 lb) with a length of 10–179 cm (4 to nearly 6 ft.). Both male and female mountain goats grow black horns reaching 15–28 cm (5.9–11.0 in) in length. After they are about 22 months old, the horns are visible and it is possible to tell the age of a mountain goat by counting the number of rings on its horns. Two of the individuals in this image are too young to have grown horns yet.
There are an estimated 100,000 Mountain Goats in North America. They are protected from the elements by long woolly white double coats that they shed in spring. Their coats are highly specialized consisting of fine, dense wool undercoats covered by an outer layer of longer, hollow hairs. Their coats help mountain goats survive winter temperatures as low as −50 °F (−46 °C) and winds of up to 160 kilometers per hour (99 mph). The average lifespan of a mountain goat is 9 to 12 years.