Citation. Figala, J.; Tester, J. R. 1986. Comparison of seasonal rhythms of activity of grey squirrels (Sciurus carolinensis, Rodentia) in captivity and in the wild. Vestnik Ceskoslovenske Spolecnosti Zoologicke 50:33-48.   [1046  LTER]

Abstract. Seasonal changes in the activity rhythm in captive grey squirrels (Sciurus carolinensis) were recorded by a photocell system at the Cedar Creek Natural History Area, Minnesota. Photocell recordings from grey squirrels near the Arctic Circle at Kuusamo, Finland and at Andechs, West Germany were analyzed and compared with those from Cedar Creek. Activity rhythms of wild squirrels, and also of the captives, were monitored by radio telemetry at Cedar Creek. The duration of activity time (a) in both captive and wild squirrels did not follow the duration of the photoperiod throughout the year. The very short a in late winter might be under the control of exogenous factors other than light, especially in wild squirrels. The marked increase in length of activity in September in wild squirrels w as probably related to mast harvesting behavior. Seasonal differences in phase angle and duration of activity indicate larger variations in wild than in captive squirrels. Secondly, our data on grey squirrels suggest that day-active mammals exhibit larger variations in phase angle differences and duration of activity than day-active birds.