Interspecific Difference in Seed Dispersal Characteristics between Japanese Macaques (Macaca fuscata) and Sympatric Japanese Martens (Martes melampus)

We compared the characteristics of seeds within faeces between semi-terrestrial Japanese macaques ( Macaca fuscata ) and sympatric arboreal Japanese martens ( Martes melampus ) in Shiga Heights, central Japan. We collected faecal samples of the two mammalian species for 1 year ( n = 229 for macaques and n = 22 for martens). We then compared the proportion of seed occurrence, life-form composition, number of seeds and species richness within single faecal samples, and the seed intact ratio between the two mammalian species. We detected seeds from 20 and 7 species from macaque and marten faeces, respectively. Macaque faeces contained seeds of multiple strata, while marten faeces contained no herbaceous plant seeds. Seed sizes within faeces showed no interspecific difference. For macaques, seeds were found within faecal samples collected in late spring to late fall, while for martens, seeds were found between summer and winter. The proportion of seed occurrence was greater in summer (both species) and fall (macaques), which implied that the seed dispersal roles of macaques and martens was greater in these seasons. The mean seed number (across species), intact ratio of seeds (high for both species) and seed species richness within single faecal samples of macaques and martens showed no significant differences, but for several species, martens defecated more seeds than macaques and showed higher intact ratio. Our study indicates that sympatric mammals in the temperate regions of Japan contribute differently to seed dispersal in forest ecosystems.