Dall sheep is a wild sheep that lives in the mountainous regions of North America, in an area that extends into the Northwest Territories, northern British Columbia, the Yukon Territory and Alaska. The name of the species, Dalli, derives from William Healey Dall, an American naturalist who studied them in their habitat for a long time.
They browse a variety of plants such as grasses, sedges and even shrubs such as willow, during different times of the year. They also acquire minerals to supplement their diet from mineral licks. Like other Ovis species, the rams engage in dominance contests with their horns.
The sheep inhabit the subarctic and arctic mountain ranges of Alaska, the Yukon Territory, the Mackenzie Mountains in the western Northwest Territories, and central and northern British Columbia. O. dalli are found in areas with a combination of dry alpine tundra, meadows, and steep or rugged ground.
This combination allows for both grazing and escape from predators. Changes in Dall sheep abundance, distribution, composition and health may indicate changes happening with other species and ecosystem processes. The sheep live in alpine or high mountain areas.
These areas are expected to experience significant changes associated with climate change. Changes may include shifts in locations of plant communities, diversity of plant species, and local weather patterns, which may affect sheep distribution and abundance.
As a result, low-growing alpine species may be out-competed or shaded by the encroaching woody plants. Changes in the seasonal availability and diversity of alpine plants may affect Dall sheep populations by altering sheep diets and consequently where they can live in mountain parks, as well as ewe pregnancy rates and lamb growth and survival.
Research has shown that the use of these subspecies designations is questionable. Full color interplay occurs between the white and dark coats of the species with intermediate color populations, called Fannin sheep, found in the Pelly and Ogilvie Mountains in the Yukon Territory.
The mitochondrial DNA evidence has shown no molecular division along current subspecies boundaries, although the nuclear DNA evidence may provide some support.