[La fin de la période de l'hibernation des marmottes. Closing period of marmots hibernation].

Résumé

the closing of hibernation is one of the unsufficiently studied problems of marmots biology. analisis of the dates of breeding shows that the marmots begin their activity before the entrance from burrows. but there are no clear dates about particularies of this process. such situation is connected with the difficulties of investigation in nature. this work was made at the marmots farm near moscow. more then 700 marmots (M. bobac and M. caudata) were under observation. All marmots may be divided into two groups for their temperature dynamic in the closing period of hibernation. The first - animals which are ready to breed. The second - weak adult and young animals. Body temperature of the animals of the first group became high and stable during the February. Extremal factors (air temperature, starvation didn't influence at this process. It's nesessary to point out that this process wasn't simultaneous for all population. The first marmots awoke at the end of January, the last - at the beginning of March. Body temperatures of the most part of the weak adult and some young marmots increased in this period too, in spite of starvation and low air temperature. But it wasn't stable. Fluctuation of body temperature was individual for every concret animal. The most weak of them often decreased the temperature to the +5 deg. after some days of high one (deep hibernation). The fluctuation of body temperatures in strong animals from this group weren't considerable (25-38 o C.). Allweak adult and young marmots increased their body temperature to constant high level (36-38o C) only after the beginning of constant feeding. Those facts show that endogenic mechanisms connected with breeding period definit the end of winter hibernation of breeding animals. Such mechanisms influence on body temperature of weak adult and young marmots too. But the external mechanisms (feeding) are the main for them. It is evident that the same processes takes place in nature. This model shows the energetic strategy of marmot populations in the closing period of hibernation.