The temperature niche of the steppe marmot Marmota bobak, Müller (1776) in the course of hibernation [La niche de température de la marmotte des steppes Marmota Bobak, Müller (1776) au cours de l'hibernation].

Résumé

Before hibernation, marmots close their burrows to prevent convection transfer of heat inside the burrow. As a result, the temperature inside the burrow differ only little from that of enclosing soil. Using data on the soil temperature published in the directory on USSR Climate, I described the temperature regime of the burrows (depth from 140 to 450 cm) of the steppe marmot in the course of hibernation (from August to April), within the species range, and in the subspecies range. Taking into account the entire thickness of the earth enclosing the hibernation chamber, the dates of the beginning and the end of hibernation at a temperature of 2-4° C. The temperature amplitude of the soil at a depth of hibernation chamber within the hibernation period in local populations of the steppe marmot is 8-10° C. The hibernation temperature regime differs significantly between the subspecies. M. b. bobak winters at a temperature of 3-4° C higher than M. b. schaganensis. In the range of M. b. schaganensis marmots start hibernation one to two months earlier than in the range of M. b. bobak. The cause of subspecies differences in the dates of the onset of hibernation appears to lie in the zonal properties of seasonal changes in air temperature. A favorable factor for survival of hibernation by marmots is the temperature dynamics from the onset of hibernation to the advent to the surface. In the course of hibernation, the earth temperature declines gently and at a rate that hardly exceeds 1° C per month.