FEATURES OF THE BROWN BEAR (URSUS ARCTOS) SEASONAL ACTIVITY IN THE BEREZINSKY BIOSPHERE RESERVE

Abstract

The data on the seasonal activity and phenology of its main stages of the brown bear (Ursus arctos Linnaeus, 1758) in 2022—2024 were collected in the Berezinsky Biosphere Reserve, which is located in the northern part of Belarus and covers an area of 86,100 hectares. Forests occupy 89 % of its territory and belong to the subtaiga broadleaf-spruce forest subzone. The primary investigation methods were year-round palmar callus mapping, with individual bear identification whenever possible, and use of camera traps.
The average annual date for males to leave their dens is March 16, and for females — April 5. The mating season lasts from late April to the second half of June, lasting up to 2 months. Denning occurs in late November — early December. Females with yearling cubs den earlier than other age and sex groups.
During the wakefulness period, brown bears exhibit a pronounced unimodal seasonal activity pattern. Its peak is recorded in May, during the mating season. In March and April, after awakening, activity increases. High activity in April is associated with preparation for mating, active movements and marking behavior of males. By June activity stabilizes, then gradually decreases by the end of November. The brown bear's period of wakefulness can be divided into three stages: post-denning, mating, and fattening. During the post-denning period, bears are inactive; only closer to the mating season males begin active marking. The mating season is characterized by the highest activity of brown bears, when breeding adult individuals move a lot. The fattening period (hyperphagia) is of low physical activity with minor fluctuations, associated with changes in feeding areas. No significant differences in seasonal activity are observed between males and females.