Specific features of hibernation in the black-capped marmot (Marmota camtschatica) from Ïakutia [Caractéristiques spécifiques de l'hibernation chez la marmotte à tête noire].

Résumé

Experimental investigations showed that some additional adaptations appeared in black-capped marmots living in conditions of cold climate and permafrost. In order to keep an optimal temperature in winter nests, marmots plug up their entrances with "puff" stoppers which have air space inside. They use a great quantity of nest bedding, "plaster" nest walls and thicken the aboveground layer with crushed stone. The animals reduce energy expenditures by lowering their body temperature down to 0 degree C and hibernating in large groups, Their torpor periods become longer, and in arousal periods, their body temperature is kept at the lower level than at the normothermic state, A transitional period (about two weeks) precedes the beginnig of deep hibernation. Stable hibernation was observed at temperatures of -2 to +2 degrees C. In winter, marmots wake up periodically independently of hibernation conditions. Age differences in duration of bout and arousal as well as in the quantity of energy expenditures were observed. The dynamics of heart activity at different stages of hibernation were found, The main factor determining successful hibernation is environmental temperature and its fluctuation.