Alaska’s Big Five; Chapter Five:
Dall Sheep, Ovis Dalli dalli, can be found throughout Alaska’s mountain ranges. Dall Sheep prefer relatively dry country, their territory is the open alpine ridges, mountain meadows and steep slopes. They like to keep an extremely rugged “escape terrain” close at hand, and are not often found below tree line.
The rams are known for their massive curling horns. The ewes have shorter, more slender and less curved horns. The males live in groups and seldom interact with the females until breeding season, which is in December.
Lambs are born in late May to early June. Ewes usually reach breeding age at 3-4, and have one lamb each year after that. The lambs are most vulnerable during their first 30-45 days of life, and mortality rate is high during this time. Wolves, black & brown bears and golden eagles are the main predators.
Dall sheep horns grow steadily from early spring to late fall, but tend to slow, if not stop growing altogether, during the winter months. This leaves growth rings on the horns called annuli. These growth rings can help identify the age of Dall Sheep. In the wild, 12 years of age is considered old for a Dall Sheep, but rams have been identified as high as 16, and ewes up to 19 years of age. A Dall Sheep ram can weigh up to 300 pounds, with the ewes being about half that weight.
Between 1990 – 2010, Dall Sheep numbers had dropped by 21%, from 56,740 to 45,010. Numbers started increasing up until 2013, when a later than average snowfall put a damper on recovery efforts. Dry, heavy snow loads appear to have little effect on sheep population, but the heavy, wet snowfalls, with a frozen crust can make foraging and travel difficult. Freezing rain has also become more prevalent. All of these factors contribute to more avalanches, which have become a significant cause of death for Dall Sheep in the state.