Factors affecting selection of resting site type by pine marten in primeval deciduous forests [Bialowieza National Park, Poland]

The resting site choice of 14 pine martens Marten martes (Linnaeus, 1758) (6 males and 8 females) in Białowieża National Park (BNP), north-eastern Poland, was analysed. The radio-collared martens were located 1,790 times in 877 different resting sites. For both males and females, arboreal resting sites (cavity and nest) constituted over 95% of the resting events. Cavities were used more frequently than nests. Resting site use differed significantly between sexes and seasons. Females rested in nests less often than males (especially in spring), but selected cavities more frequently than did males. Females with young chose only cavities, whereas non-breeding females often rested in nests. Weather conditions influenced the choice of resting sites in various months. For males, temperature was a significant factor from October to May, for females from December to March and in June-July. Martens rested in nests when mean ambient temperatures were higher, in cavities or on the ground when tempera­tures were lower. In summer and winter, when average humidity was high males often rested in cavities or places on the ground. When winds were strong or snow cover was deep, martens chose ground sites. In years of high squirrel density, frequency of nest use by marten increased. During severe winters, frequency of use of ground sites increased. Oak, lime, and spruce trees were frequently used by martens (males - 85.7% and female - 70.6% of all resting sites). Males rested in spruce more often than females, while females used oak and lime more often than males. Martens selected lime and oak, and avoided hornbeam trees. Literature on winter resting sites of pine martens in Europe was reviewed. It was shown that in northern Europe martens rested primarily on the ground. In the temperate zone, martens used cavities in trees (eastern Europe) on nests (western Europe).