Dall's Sheep - Life in the Mountains is Changing
Dall’s sheep, a subspecies of thinhorn sheep, are an icon of northern mountainous landscapes. These completely white sheep live in alpine pockets of northwestern North America, extending from B.C., through the Yukon/NWT, and into Alaska. Their global population is estimated at less than 110,000, although accurate numbers can be hard to get due to the remoteness of most of their range. Dall’s sheep are of great importance to the past and present culture of Indigenous peoples and are highly valued by hunters and wildlife enthusiasts.
This species is experiencing rapid change in the subarctic mountains they live. These sheep have evolved to inhabit some of the most inhospitable ranges on earth. Extremely cold, long winters and short summers characterize their northern environment. However, climate change may be impacting Dall’s sheep in ways they haven’t had time to adjust to. Climate conditions are changing faster in the north compared to other parts of the world, particularly in winter and at high altitudes. Winter temperatures across Yukon and Alaska are warming at almost 1 degree Celsius per decade. Sheep are feeling the pressure.
As winter temperatures increase, there are more freeze-thaw and rain-on-snow events, which form crusts within the snowpack. Research has shown these events may be linked to reduced survival rates; ice crusts can impede access to forage, make movement more taxing, and influence sheeps' ability to escape predators. Additional climate-related factors such as cold fall and spring temperatures, late spring snow, and dry summers have also been related to lower survival. Within the last decade, range-wide survey counts have found evidence of more extreme population highs and lows, and in some cases, serious declines.
Given their excellent adaptations for living on the edge of what’s possible for a mammal, when these sheep struggle it is a signal of change at an ecosystem level, affecting animals, plants, and natural processes. Dall’s sheep have proven resiliency – but is it enough?
Read MoreThis species is experiencing rapid change in the subarctic mountains they live. These sheep have evolved to inhabit some of the most inhospitable ranges on earth. Extremely cold, long winters and short summers characterize their northern environment. However, climate change may be impacting Dall’s sheep in ways they haven’t had time to adjust to. Climate conditions are changing faster in the north compared to other parts of the world, particularly in winter and at high altitudes. Winter temperatures across Yukon and Alaska are warming at almost 1 degree Celsius per decade. Sheep are feeling the pressure.
As winter temperatures increase, there are more freeze-thaw and rain-on-snow events, which form crusts within the snowpack. Research has shown these events may be linked to reduced survival rates; ice crusts can impede access to forage, make movement more taxing, and influence sheeps' ability to escape predators. Additional climate-related factors such as cold fall and spring temperatures, late spring snow, and dry summers have also been related to lower survival. Within the last decade, range-wide survey counts have found evidence of more extreme population highs and lows, and in some cases, serious declines.
Given their excellent adaptations for living on the edge of what’s possible for a mammal, when these sheep struggle it is a signal of change at an ecosystem level, affecting animals, plants, and natural processes. Dall’s sheep have proven resiliency – but is it enough?
