Sociology of the feeding strategy of Japanese monkeys

Research Project

Project/Area Number	61540474
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	生態学
Research Institution	Kyoto University
Principal Investigator	SUGIYAMA Yukimaru Professor, Primate Research Institute, Kyoto Univ., 霊長類研究所, 教授 (20025349)
Co-Investigator(Kenkyū-buntansha)	MORI Umeyo Researcher, Primate Research Institute, Kyoto Univ., 霊長類研究所, 教務技官 (30109087) MORI Akio Associate Professor, Primate Research Institute, Kyoto Univ., 霊長類研究所, 助教授 (50027504) OHSAWA Hideyuki Associate Professor, Primate Research Institute, Kyoto Univ., 霊長類研究所, 助教授 (60027498)
Project Period (FY)	1986 – 1987
Project Status	Completed (Fiscal Year 1987)
Budget Amount *help	¥1,500,000 (Direct Cost: ¥1,500,000) Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1986: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywords	Japanese monkeys / population parameters / population growth rate / social structure / reproductive success / feeding strategy / 個体群成長 / 繁殖効率 / 採食生態 / 採食速度 / 採食空間 / 採食時の個体間関係
Research Abstract	In order to re-examine social behavior of Japanese monkeys in relation to the feeding strategy, studies were conducted at Kinkasan, Takasakiyama, Koshima, and Ryozenyama. 1. The monkeys of the Kinkasan troop increased number of food patches to visit in a day, and expanded the duration of feeding time against the food shortage in winter. However, difference was not found for these activities depending on the difference of dominance rank. 2. Population parameters of Takasakiyama troops remarkably decreased since 1975 when artificial food supply have been much reduced. This fact shows that food intake directly affects reproductive succes of monkeys. The amount of intake of artificial food showed difference for difference of dominance rank among matri-lines, and females of higher rank showed high reproductive success than those of lower rank. However, the preliminary results showed no difference of the amount of food intake in the forest depending on rank difference. 3. Artificial food supply … More for the Koshima troop is reduced minimally, only for the facilitation of observation. The longitudinal change of dominance rank among females was examined in relation to their reproductive success, which was low for lower ranking females among the highest matri-line. The reason for their low reproductive success was analyzed. That is, they were frequently attacked in aggressive interactins, or they showed most unstable dominance rank; they showed drastic drop of dominance rank and high mortality rate after drop of rank. The difference of rank strongly affected their social attitude and their feeding strategy. 4. The reproductive success of Ryozenyama troop increased for lower ranking females after division of the mother troop into two, one consisting of higher ranking kins and the other lower ranking. The inferior feeding condition of lower kins must have changed to the same condition with that of the higher kins after the troop division. The present studies indicate that the difference of reproductive success depending on difference of dominance rank is much enhance in the artificial condition, and that it is much reduced in the natural condition. Less