The dietary structure and distribution patterns in pine martens Martes martes in situations of different food supply in the coniferous forest of north-eastern Belarus were investigated. A total of 1222 scats were analysed, and snowtracking of pine martens was done each winter. Seven pine martens were radiotracked (n=7549 radiolocations). Abundance of the main prey was monitored. The pine marten acts both as an active predator, mostly taking many species of rodents and birds, and as a gatherer, feeding on fruits and scavenging for carrion. In the ecologically poor woodland on sandy soil the predator specializes in feeding on carrion in the cold season, and on berries in the warm season. The richer food supply in the woodland on clay soil results in a markedly higher population density and fairly even distribution of pine martens than those in the woodland on sandy soil, where pine martens mainly live in valley habitats. The winter density of bank voles drives the pine marten numbers. Also biomass of carrion is a crucial factor determining the predator density by late winter.
The structure of the vertebrate predator community in north-eastern Belarus has been examined before and after naturalization of the American mink and raccoon dog. Species composition of the community, population density and biomass, portion of each species in the pooled community density and biomass, species body mass and size structure of the community were investigated. The community consisted of 36 native predator species, and 11 other predator species were sporadically registered in the area in both periods before the American mink and raccoon dog expansion and after the introduced species have reached a high population density. Separating predator species into four size groups, we found that in terms of total density the largest portion of the community belonged to small predators, while large predators formed the smallest portion. In terms of total biomass, the larger medium-sized predator group predominated over other size groups. Despite decline in the populations of ten native predator species, the total community density and biomass as well as portions of different size groups appeared to be very similar before and after naturalization of the introduced predator species.