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.
A predator removal study was done in Finland to reveal the possible effects of mammalian predators on the breeding success of ducks. Predator removal/protection from hunting was most effective in northern Finland. Also in eastern Finland predator removal had some influence on predator numbers, whereas its impact on predator numbers was not so evident in southern Finland. In southern Finland, no increase in the breeding success of ducks was observed in the predator removal area, whereas in northern Finland the relative reproduction rate of diving ducks increased in the removal area and that of dabbling ducks declined in the control area. In eastern Finland, the breeding success of ducks declined in both areas. There was a positive relationship between the raccoon dog index and the relative reproduction rate of dabbling ducks in southern Finland, indicating that raccoon dog numbers probably are of minor importance for the breeding success of ducks. On the contrary, there was a negative relationship between the fox and marten indices and the breeding success of ducks in some areas. Marten and fox removal may thus have a positive effect on the breeding success of ducks in Finland. The effect of the American mink could not be verified in this study.