Climate change and the conservation of marmots

Abstract

Conservation of marmots, large ground-dwelling squirrels restricted to the northern hemisphere, was impacted by direct human activity through hunting or modifying ecosystem dynamics. Regulating human activities reduced the threat of extinction. Climate change, an indirect human impact, threatens marmot survival through global warming and extreme weather events. Most marmot species occupy a harsh environment characterized by a short growing season and a long, cold season without food. Marmots cope with seasonality by hibernating. Their large size increases the efficiency of fat accumulation and its use as the sole energy source during hibernation. Marmot physiology is highly adapted to coping with low environmental temperatures; they are stressed by high heat loads. Global warming since the last ice age reduced the geographic distribution of some of the 15 species of marmots. Recent warming resulted in a movement upslope of their lower elevation boundary. This process likely will continue because warming is associated with drier unpalatable vegetation. Drought reduces reproduction and increases mortality; thus decreased summer rainfall in the montane environments where marmots live may cause local extinction. Snow cover, a major environmental factor, is essential to insulate hibernation burrows from low, stressful temperatures. However, prolonged vernal snow cover reduces reproduction and increases mortality. Montane areas currently lacking marmot populations because vernal snow cover persists beyond the time that marmots must begin foraging may become colonized if warming causes earlier snow melt. This benefit will be short-lived because decreased precipitation likely will result in unpalatable vegetation. Although some marmot populations are physiologically adapted to a warmer climate, global warming will increase too rapidly for any significant evolutionary response to dryness. The species that live in high, alpine meadows where tree and shrub invasions occur are most threatened with extinction. Captive breeding can preserve marmot species in the shortrun, but is impractical over the long-term. Widespread species are unlikely to be endangered in the foreseeable future, but local, low elevation populations will be lost.