Sleeping-site preferences of wild Japanese macaques
(Macaca fuscata): the importance of nonpredatory factors
I investigated sleeping-site preference in habituated wild Japanese
macaques (Macaca fuscata) for each season (254 days total) on
predator-free Kinkazan Island, northern Japan, during 2000-2007. I
focused on the effectsof nonpredatory, environmental factors
(vegetation type, altitude, and topography), to which little attention
has been paid. Macaques used 24-79 sleeping sites in each season (227
sites in total, all on the ground). The frequencies of sleeping sites
in each season followed a Poisson distribution, except for spring when
several sites were used repeatedly. In spring macaques preferred
sleeping in Zoysia japonica grassland, where several staple food
species (Berberis thunbergii and Zelkova serrata) are abundant in this
season. In summer and fall macaques avoided sleeping in high-altitude
forest dominated by Fagus spp., and in the latter season they also
preferred Zoysia grassland; these preferences likely reflect an
avoidance of strong winds rather than the lower food availability at
higher altitudes. In winter macaques avoided sleeping in Zoysia
grassland, mainly due to the poor food supply. Macaques preferred
valleys to ridges in spring and winter, possibly due to greater
densities of shelters such as rocks and fallen trees that facilitate
energy conservation in the face of strong/cold winds at night.
Additional quantitative data for other mammalian species are needed
for generalizations to be made about the importance of nonpredatory
factors on sleeping-site preferences.
Journal of Mammalogy 92:1261-1269JAN/16/2012
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