Date of Award

Summer 8-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)


Ecology and Environmental Sciences


Danielle Levesque

Second Committee Member

Amber Roth

Third Committee Member

Cynthia Lofin


Climate change may potentially alter a species’ range distribution and thus the relationship between environmental temperatures and animal performance as a response to climate warming has become an important area of research. Two species of flying squirrel in North America, the southern flying squirrel (Glaucomys volans) and the northern flying squirrel (Glaucomys sabrinus) have undergone northward range shifts, with climate warming being the suspected driver. Because they are nocturnal and tree nesting, flying squirrels may be particularly susceptible to warmer temperatures, as they will experience the highest daily ambient temperatures during their resting phase. I used G. sabrinus as a study species to determine the effect of high temperatures on thermoregulation and energy use to test if thermal limits will contribute to range shifts. I measured metabolic rate and evaporative water loss under different ambient temperatures using flow-through respirometry and estimated the responses to high ambient temperatures in the field by measuring body temperature. I used climate data from Arrowsic, Bangor, and Presque Isle, Maine over recent decades to determine if temperature increases would correspond to the northward movement of flying squirrels in Maine. G. sabrinus did not show visible or physiological signs of heat stress during respirometry experiments, and an upper critical temperature was not reached at temperatures tested. Consistent daily rhythms in body temperature were observed in free-ranging flying squirrels, as predicted, and increased as ambient temperatures decreased. Additionally, high ambient temperatures were not likely to be a direct factor in northern flying squirrel range shifts, but that climate warming caused G. volans to move north and outcompete G. sabrinus.