Life in a Shrinking World: Thermal Physiology and Activity of Diurnal Alpine Mammals in Relation to Climate Change

The effects of increased global temperatures are being measured in many biological systems. Given the complexity of biological systems, their responses to a changing climate are difficult to predict. Physiologic processes are particularly susceptible to temperature, leading to a species specific optimal range of habitable temperatures. As global temperatures increase, species will be exposed to a changing range of potentially stressful temperatures, especially in species currently living at their thermal limits (e.g., alpine mammals). Warming temperatures may force alpine species to move to higher elevations to maintain thermoneutrality. Ultimately, if temperatures increase as predicted, alpine mammals may be unable to move higher and may face localized extinctions. I hypothesize that, many alpine mammals are currently living at the upper range of their thermoneutral zone and, in response to warming temperatures; alpine mammals will experience ambient temperatures above their upper critical temperature which will limit their activity period. I will measure the metabolic thermoneutral zone of small mammals in relation to temperature at four montane sites in the western U.S. We will focus on small diurnal mammals (chipmunks and pikas) as they are prolific and susceptible to high temperatures. The proposed study will not only provide sorely needed information on the basic thermal requirements of numerous alpine small mammals in the U.S., but that information can be used to generate physiologically relevant models to predict future changes in the altitudinal ranges of these species.