NPS Photo / Katie Thoresen
Rams resemble ewes until they are about 3 years old. After that, continued horn growth makes them easily distinguishable. Their horns grow steadily during spring, summer, and early fall. In late fall or winter horn growth slows and eventually ceases. This is probably a result of changes in body chemistry during the rut. This pattern of horn growth results in rings called annuli that are spaced along the length of the horn. A sheep’s age can be accurately determined by counting these annuli. Researchers have recorded rams as old as 16 years and ewes as old as 19 years. More typically, a 12-year-old sheep is considered very old. As rams mature, their horns form a circle when seen from the side. Ram horns reach half a circle in about two or three years, three-quarters of a circle in four to five years, and a full circle or "curl" in seven to eight years. Dall rams normally do not breed successfully until they approach dominance rank (at full curl age and size).
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Denali is home to a daily life and death drama for many animals, though the 'big five' mammal species stand out in the minds of many visitors. In addition to the opportunities for viewing or photographing Interior Alaska’s large mammals, Denali is a great natural laboratory to study the species and their interrelationships. Unlike the rest of Interior Alaska, the Denali carnivore/ungulate community has been little affected by human harvests for several decades. Read more
Check out a yearly update of population estimates for "the Big Five" species of Denali - wolves, caribou, Dall sheep, moose and bears. Read more
Discovery how and why scientists monitor Dall sheep in national parks throughout Alaska. Read more
Emerging archaeological evidence suggests that upland landscapes of central Alaska were seasonally important to early humans as hunting grounds, for animals like Dall sheep. When and how humans adapted to this landscape is unknown, and so archeologists study such areas to get a clearer picture of the lives of early humans in this part of the world. Read more