Human effects on habitat use of Japanese macaques (Macaca fuscata): importance of forest edges

Habitats of the Japanese macaque (Macaca fuscata) have been modified by human activities such as deforestation, conifer plantation, agriculturalization, and forest fragmentation. Such modifications likely affect habitat use of the macaques. We examined the habitat use of two macaque troops: a "forest troop" and a "cropland troop". We focused on forest edges, which have not been previously categorized as a habitat type. Both troops frequently used deciduous broad-leaved forest in autumn and forest edges in summer. The forest troop frequently used forest-grassland edges, whereas the cropland troop frequently used forest-cropland edges. The selection index for the deciduous broad-leaved forest of the cropland troop exhibited significantly higher values than those of the forest troop in summer, autumn, and winter. Since the Japanese macaque is a forest-dweller and tends to avoid open areas, both troops may have used forests more frequently. Meanwhile, a decline in food resources in the forest due to the establishment of conifer plantations and an increase in food resources due to agriculturalization may have led to more frequent use of forest edges by the macaques. Forest edges should be treated as an independent habitat for accurate assessment of macaque habitat use.