The response of European pine marten [Martes martes L.] feeding to the changes of small mammal abundance

The European pine marten (Martes martes) is commonly classified as an opportunistic predator. If this is the case, the species ought to show seasonal differences in the small mammal composition of its scats – the types of prey taken depending on their abundanc. In addition, it ought to consume the food that requires lower energy cost for their acquisition in each season. The feeding strategy of the European pine marten was studied in northwestern Spain by analyzing 209 scats collected between July 2004 and June 2005, and by seasonally trapping small mammals to obtain information on their abundance. The study area (5,722 ha) was located in a mountainous region (1,707–880 m a.s.l.) and covered with brushwood and deciduous forest (oak, birch, holly and pine). Molecular analysis of scats (PCR-RFLP) was performed to rule out the presence of the stone marten (Martes foina L.). The frequency of occurrence and biomass of the small mammals (the main prey species) preyed upon each season were compared. The pine marten consumed significantly more small mammals in the seasons in which their abundance was the lowest (winter and spring). In the autumn, when the highest number of small mammals was detected, the pine marten did not increase its predation of them. These results indicate that the European pine marten is not an opportunistic predator. Rather, the feeding strategy adopted by the species seems to be intermediate between that of an opportunist and specialist predator.