Why do some mountain animals migrate to lower elevations in winter?

In temperate mountain ecosystems, many animals migrate to lower elevations during winter primarily as a behavioral response to the highly seasonal climate and the resulting scarcity of resources.1

As winter approaches, high-altitude environments experience harsh conditions, including deep snow cover and freezing temperatures, which limit the availability of food. By descending into valleys or forested environments, animals such as bighorn sheep, elk, and various birds can access more favorable conditions where food is more accessible and the climate is less severe.2134

This vertical migration is a key survival strategy for many ungulates and birds that are not adapted for year-round life in the high alpine zone. While some species migrate to escape these adverse conditions, others remain at high elevations by utilizing different strategies, such as hibernation (e.g., marmots), caching food, or living in insulated burrows beneath the snowpack.41