OHSHIBA Nobuaki Osaka University, Faculty of Human Sciences, Technical Official, 人間科学部, 教務職員 (20283715)
IMAKAWA Shinji Osaka University, Faculty of Human Sciences, Research Associate, 人間科学部, 助手 (00211756)
KANAZAWA Tadahiro Osaka University, Faculty of Human Sciences, Research Associate, 人間科学部, 助手 (30214430)
NAKAMICHI Masayuki Osaka University, Faculty of Human Sciences, Associate Professor, 人間科学部, 助教授 (60183886)
MINAMI Tetsuhiro Osaka University, Faculty of Human Sciences, Professor, 人間科学部, 教授 (40030043)
We have investigated the life histories of Japanese monkeys (Macaca fuscata) in a free-ranging group for more than 30 years. We have known for some time that as juvenile males mature they gradually decrease their interactions with matrilineal relatives in the central area of the group and spend more time in the peripheral area. Eventually, between the ages of three and eight, most of the young males disappear from their native group. This facilitates inter-group breeding. This male exodus is extremely important to understand, because it is the primary source of breeding between otherwise genetically-isolated groups. Our project aims to investigate the geographic movements of such males who gradually peripheralize and exit from the native group.
Observations were made on two free-ranging groups of Japanese monkeys, one is Katsuyama Group in Okayama prefecture, and the other Minoo Group in Osaka prefecture.
The target monkey stayd with the group during the most of research period. The grou
p moved within a limited area around the feeding site and sleeping sites. The spots reported by Argos system, however, scattered over larger areas than the target monkey was presumably foraging. When the location data fell into the nomadic range of the group or near by, we regarded it as "hit". The location information of CLASS 3 which has the best accuracy, and CLASS 2 which has the second best accuracy, were all "hit". The rate of "hit" for CLASS 1 which has the third best accuracy, amounted to 50 %. The rate of CLASS A amounted to 42.9 %. CLASS 0 (0%) and CLASS B (5.3%) were not reliable information. Thus, the information by Argos system may not be applicable for tracking monkeys within a small area, but may be useful for tracking dispersing males for long-distance.
Young adult males of 5- to 7-year-old were observed on their allocation in and around the group and on their social interactions with other group members by the focal animal sampling method. We found two types of males : one was relatively easily found in and around the group, staying comparatively long time with the group's central members, and the other was rerely found in and around the group, moving widely. Less