NUMBER, SEX AND AGE STRUCTURE OF THE BROWN BEAR(URSUS ARCTOS) POPULATION IN THE BEREZINSKY BIOSPHERE RESERVEAND ADJACENT AREAS

Abstract

Berezinsky Biosphere Reserve is located in the northern part of Belarus on the area of 81,6 ha. Forests occupy 89% of its territory and belong to the subzone of subtaiga deciduous-spruce forests. They are represented by four groups of forest formations: boreal coniferous – 53%, broad-leaved – less than 1%, deciduous swamp forests – 35% and deciduous secondary – 11%. The total area of the brown bear census is over 130.000 ha. Work on counting and determining the sex and age structure of local population has been held since 2020, though most data was collected during 2022 and 2023 using widely spread methods, especially measuring the size of animals’ footprints (palmar callus).

The number of brown bears (Ursus arctos) in Berezinsky Biosphere Reserve and on adjacent territories (130.000 ha) was 88–98 individuals, among which 24 were cubs. The protected area alone is inhabited with 54–64 bears and 17 cubs. The density of brown bear population on the whole study area was 10 individuals per 100 km² or 1 individual per 1000 ha of suitable area. A stable group of brown bear with constant number has formed in the reserve, and its growth has apparently stopped.

Females are the most numerous group – 31% of the total population number. Moreover, 9 of 22 (41%) females counted in 2024 had cubs. Males make up about 26% (18 individuals were counted within the reserve boundaries). The whole study area is inhabited with 27–29 males (30%). The third group consists of medium-sized bears, the sex of which could not be defined; 14–22 individuals (17%) were counted.