Mountain goats are built to thrive where few others can. Though they aren’t “true” goats, but part of a unique group of goat-antelopes, they have mastered life on the edge of the alpine world. Their stocky, muscular bodies are covered in a thick, woolly coat of snow-white fur that helps them blend into snowy surroundings. This coat has two layers: a dense, fine underwool beneath longer hollow guard hairs. Together they insulate so well that mountain goats can withstand winter temperatures of −46 °C (−51 °F) and brutal winds on exposed peaks.

Each spring, they shed this coat in clumps by rubbing against rocks and trees, with adult males molting earlier in the season and pregnant females shedding later. By mid-summer a goat might look scruffy with patches of loose fur, but a fresh plush coat grows in by autumn, ready for the next snows.

Both males and females have short beards, stubby tails, and sharp black horns that sweep up and back from the skull. These horns reach about 20-30 cm (8-12 in) and are never shed; each year, a new growth ring forms, allowing age to be estimated by the ridges. A full-grown mountain goat stands about 1 m (3 ft) at the shoulder. Males, known as “billies,” are larger and heavier than females, or “nannies,” sometimes by as much as 30 percent.

Their feet are specialized climbing gear, with cloven hooves that can spread wide on rock, rubbery pads under each toe for grip, and sharp dewclaws at the back that catch if they begin to slip. Their body are deep-chested but narrow, which allows them to balance on tight ledges and even turn around on steep faces. Strong shoulder and neck muscles help them pull themselves up near-vertical rock. These physical tools equip the mountain goat for life on the edge, but behavior plays just as big a role in their survival.