[Seasonal peculiarities of the ground squirrel (Spermophilus undulatus) and Wistar rats circadian activity].

The seasonal peculiarities of the circadian activity of hibernator, Yakutian long tail ground squirrels (S. undulatus) (n = 35) and non hibernator, Wistar rats (n = 35), were studied. The locomotor activity was registered in each subject individually during 5-17 days by means of "Animex" in the different periods of annual cycle. It was shown that ground squirrels were animals with daily type of activity. On the contrary, the Wistar rats demonstrated nocturne type of locomotors activity. The active period in rats was longer than in ground squirrels. It included not only at night, but morning time in spring, and daytime--in summer. The circadian differences between hibernators and non-hibernators were kept during all annual cycle at night time, but in daytime--only in spring and summer time.