Hibernation and breeding of Marmota bobac [Hibernation et reproduction de marmota bobac].

Résumé

The endogenic mechanisms of termination of hibernation connected with breeding influence all steppe marmots except very weak ones. They cause the increasing of arousals and the mean body temperature in the second part of winter. In that period animals prepare for breeding. In pre-breeding period testicles of males and vaginas of females enlarge. The cells, typical for estrus, sometimes are found in vaginal smears. Adult animals which weight losses during the hibernation were not great, increase their body temperature to the constant high level in 2-3 weeks. Meanwhile the estrus of females becomes constant and testicles of males reach the maximal development. These marmots support the high and constant level of metabolism during 1-2 months without any food, even in the period when their body mass becomes less in comparison with unbreeding animals. The young marmots and adult animals, which weight losses during hibernation are large, are characterized by the unstable body temperature, underdeveloped testicles and broken estrus during some time. In this period the mean index of their body temperature is rather high. Afterwards they fall in the deep hibernation again.