Dall Sheep

In the high country of Alaska, surrounded by mountain peaks, look up. There on the steep, rocky slopes are a group of white spots, tiny in the distance, like a string of pearls. They are Dall sheep, nimble and fearless on ground where few predators dare tread.

Dall sheep, named after American naturalist William Healey Dall, are wild sheep found only in Alaska and western Canada. They are uniquely suited to the rugged alpine heights they inhabit. Their thick white coat, good camouflage against snow, consists of a wool undercoat covered with long, stiff guard hairs which are hollow, helping to regulate body temperature. Their hooves are specialized with hard outer rims to grip rocky surfaces, and soft concave centers for extra traction. Thus, they are sure-footed on treacherous mountainsides, safer from wolves, coyotes and bears.

Males (rams) usually weigh between 160-180 pounds. Females (ewes) are smaller, weighing 100-110 pounds.

Average life span is 12-16 years. Both sexes have horns, but they are easy to tell apart. Ewe horns are much thinner with little curl. Rams have distinctive horns that are thicker and curl around each side of the head, growing to a "full curl" by the age of seven or eight. Their horns grow throughout their life, much during the summer but not in winter.

This on-and-off cycle creates a pattern in their horns, called annuli, indicating how old an individual is. Before they mature, ram horns look much like ewe horns until they begin to curl at three years of age.

Being herbivores, Dall sheep find lots to eat in summer when alpine meadows offer a banquet to feed on, and even the rocky slopes grow grass or herbs to nibble on. Sometimes they travel to salt licks, to eat mineral-rich inorganics to supplement their diet. They eat and grow fat while they can. Come winter there is much less to choose from. Sheep forage where they can, finding frozen grasses, lichens or moss. They may lose 16% of their body mass over these cold dark winter months. Dall sheep are social animals, living in groups according to sex and age. Rams form bachelor groups in which all members are ranked by age and strength. They choose the best foraging areas so they can bulk up. Here is where the rams will engage in head-to-head fights for position. Two rams of comparable size get a running start to collide horns-to-horns with each other, the impact ringing half a mile away. Extra-thick bone protects their brains in these fights, but injuries can happen. Ewes, on the other hand, form nursery groups of mothers, lambs and young rams. They choose the steeper places where risk of predators is lower. Often one or two ewes will tend the little ones, allowing the rest of the ewes feed.

Adult rams and ewes do not come together until November and December, mating season for Dall sheep. Rank counts. A dominant ram will breed with a ewe, and guard her for about three days before he finds another ewe to mate.

Younger rams of lower rank have less chance of mating. After mating is completed the rams and ewes go their separate ways again for winter, descending to lower elevations with less snow to find food.

Ewes have one lamb per year, beginning at age 3 or 4. As birth nears, ewes seek protection from predators in rugged cliffs. Lambs are born in late May or early June, able to stand within 30 minutes of birth and able to travel within a day. They begin feeding on plants by two weeks old. They are weaned within 5 months--if they survive. Even golden eagles prey on the very young. In the first 30-45 days of life lambs are at highest risk of loss.

Because of the difficult terrain the Dall sheep inhabit, they may not be the first choice for human hunters. Caribou or moose habitat may be easier to reach. However, indigenous peoples have hunted Dall sheep in these mountains for centuries. Sheep are valued not only for their meat, but for their hide, which is used in the making of warm clothing.

Sport hunting of Dall sheep is permitted in the National Preserves, for those ready to challenge the heights the sheep frequent.

Biologists are concerned that climate change may alter Dall sheep habitat and threaten the health of the sheep population. The effects of climate change may encourage the growth of woody shrubs at higher elevations, potentially diminishing the vegetation that the sheep depend upon. Warming weather could mean deeper snow or more icing events, making winter foraging much more difficult. Scientists are monitoring these possibilities.

For now, the Dall sheep population of Alaska is deemed healthy, currently estimated at 70,000-75,000 individuals.

Denali National Park was created for the protection of these remarkable animals, to the delight of thousands of tourists each summer. As you enter the high country of Alaska, watch the steepest slopes for the distant white pearls among the rocks. Or dare to climb the heights to get a closer look at Alaska's Dall Sheep.