We examined the relationship between fruit abundance and chimpanzee (Pan troglodytes) party size ... more We examined the relationship between fruit abundance and chimpanzee (Pan troglodytes) party size by comparing data from four study sites: the Kalinzu Forest Reserve, Uganda, the Djinji Camp and Guga Camp in the Ndoki Forest, Congo, and Kahuzi-Biega National Park, Democratic Republic of Congo. Although the difference in the fruit abundance between the sites was responsible for the difference in the party size between the sites, the seasonal changes in fruit abundance did not explain the changes in the party size in each study site. Across the four study sites, there were significant correlations of the mean and minimum of monthly party size with the mean of monthly fruiting-tree density, and a significant correlation of the maximum of monthly party sizes with the minimum of monthly fruiting-tree density. We proposed a hypothesis that (1) the monthly fruit abundance affects the monthly party size in the sites where the fruit availability is as low as to limit the party size during a m...
Among wild Japanese macaques, male life history traits such as tenure in a troop and dominance ra... more Among wild Japanese macaques, male life history traits such as tenure in a troop and dominance rank structure tend to be similar between study populations irrespective of habitat differences. While males transfer throughout their lives alone and voluntarily, only prime adult males takeover an alpha rank when groups contain few males but most males immigrate into a group at very low rank. Male dominance hierarchy is stable during their tenure and males usually rise in rank as more dominant males emigrate or die. Most males in any rank eventually emigrate from a group with an average of 3 years of tenure and males at higher rank do not tend to stay longer in a group than subordinate males. As they mature, males get more chances of transferring into troops higher up in the male hierarchy, and their ranks basically tend to be associated with male age. Since these aspects of male life history should bring difficulties for adult males to immigrate into a troop with relatively large number...
It is predicted that variation in intergroup relationships in group living primates reflects the ... more It is predicted that variation in intergroup relationships in group living primates reflects the cost and benefit of resource defense. We tested the applicability of the model by examining population difference, group difference, and seasonal difference in behaviors ...
We examined the relationship between fruit abundance and chimpanzee (Pan troglodytes) party size ... more We examined the relationship between fruit abundance and chimpanzee (Pan troglodytes) party size by comparing data from four study sites: the Kalinzu Forest Reserve, Uganda, the Djinji Camp and Guga Camp in the Ndoki Forest, Congo, and Kahuzi-Biega National Park, Democratic Republic of Congo. Although the difference in the fruit abundance between the sites was responsible for the difference in the party size between the sites, the seasonal changes in fruit abundance did not explain the changes in the party size in each study site. Across the four study sites, there were significant correlations of the mean and minimum of monthly party size with the mean of monthly fruiting-tree density, and a significant correlation of the maximum of monthly party sizes with the minimum of monthly fruiting-tree density. We proposed a hypothesis that (1) the monthly fruit abundance affects the monthly party size in the sites where the fruit availability is as low as to limit the party size during a m...
Among wild Japanese macaques, male life history traits such as tenure in a troop and dominance ra... more Among wild Japanese macaques, male life history traits such as tenure in a troop and dominance rank structure tend to be similar between study populations irrespective of habitat differences. While males transfer throughout their lives alone and voluntarily, only prime adult males takeover an alpha rank when groups contain few males but most males immigrate into a group at very low rank. Male dominance hierarchy is stable during their tenure and males usually rise in rank as more dominant males emigrate or die. Most males in any rank eventually emigrate from a group with an average of 3 years of tenure and males at higher rank do not tend to stay longer in a group than subordinate males. As they mature, males get more chances of transferring into troops higher up in the male hierarchy, and their ranks basically tend to be associated with male age. Since these aspects of male life history should bring difficulties for adult males to immigrate into a troop with relatively large number...
It is predicted that variation in intergroup relationships in group living primates reflects the ... more It is predicted that variation in intergroup relationships in group living primates reflects the cost and benefit of resource defense. We tested the applicability of the model by examining population difference, group difference, and seasonal difference in behaviors ...
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