Seasonal patterns in the physiology of the European brown bear ( Ursus arctos arctos) in Finland

Abstract

The physiological indicators such as body temperature, blood chemistry and hematology of seven European brown bears ( Ursus arctos arctos) were used in the present study. They were kept in either the Zoological Garden of University of Oulu (65°N, 25°24'E) or the Ranua Zoological Garden approx. 150 km NE of Oulu. Transmitters with a temperature-dependent pulse rate were implanted subcutaneously or into the abdominal cavity under anesthesia. Our data indicate that the body temperature of the bear decreases during the winter sleep to 4–5°C below the normal level (37.0–37.5°C). The lowest values, 33.1–33.3°C, were measured several times in midwinter. Hematocrit, hemoglobin and erythrocyte counts seem to be higher, and the leucocyte count lower during the denning period than in the awake bear. Plasma N-wastes were lower during the winter sleep than before or after it. The analysed blood parameters showed that plasma catecholamines and thyroid hormones decreased in the fall.