Seasonal peculiarities of behavior of ground squirrel Citellus undulatus in holeboard and open field tests

Seasonal changes in the behavior of ground squirrels Citellus undulatus (n = 35) in holeboard and open field tests were studied. It was found that the number of head dips and rearings in the holeboard and the number of crossed squares, rearings, and runs across the field center in the open field in ground squirrels during arousal between bouts at the end of the hibernation period, in the middle of March, were lower than these indices in active summer animals. A rapid restoration of all behavioral parameters after the arousal of animals from hibernation in mid-April was shown. In some cases. the behavioral parameters of activity in the holeboard and open field tests and the habituation reaction reached the values characteristic of active summer animals in a very short period of time, sometime within I day. By contrast, the locomotory and exploratory activities of animals tested in autumn (at the beginning of September and in the middle of October) were significantly lower than in summer animals, i.e. these indices decreased to minimum values 1.5-2 months prior to their entry into hibernation. The results of behavioral experiments indicate that the preparation of the CNS of hibernators for seasonal changes in the functional states is under the control of endogenous regulators. (C) 2001 Elsevier Science B.V. All rights reserved.