Matsumoto-Oda A
Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Japan.
Am J Primatol. 1999;47(3):197-207. doi: 10.1002/(SICI)1098-2345(1999)47:3<197::AID-AJP2>3.0.CO;2-3.
The social system of chimpanzees (Pan troglodytes schweinfurthii) is characterized by the fission-fusion of social groups. Several studies have reported that females are less gregarious than males. In the current study, adult female gregariousness depended on their reproductive state. Noncycling adult females (pregnant, lactating, or post reproductive) were observed in large bisexual parties less often than cycling adult females. On the other hand, cycling adult females were observed in large bisexual parties as often as males, regardless of their estrous state. More males were in parties that included cycling adult females with maximal genital swelling (estrous females) than in parties without them. Moreover, a bisexual party including more estrous females contained more males. These results suggest that large bisexual parties of chimpanzees are constructed by a dual mechanism. First, cycling adult females are attracted to parties that consist of the top ranking male and large numbers of adult and adolescent males. Second, adult and adolescent males that did not belong to parties originally are attracted by estrous females and join them. Thus, in Mahale Mountains National Park, Tanzania, bisexual parties of chimpanzees can be characterized as "parties for reproduction."
黑猩猩（黑猩猩指名亚种）的社会系统以社会群体的裂变融合为特征。多项研究报告称，雌性不如雄性合群。在当前的研究中，成年雌性的合群性取决于它们的生殖状态。与处于发情期的成年雌性相比，非发情期的成年雌性（怀孕、哺乳或生殖后期）较少出现在大型双性群体中。另一方面，无论发情状态如何，处于发情期的成年雌性出现在大型双性群体中的频率与雄性一样高。与没有处于发情期成年雌性的群体相比，有处于生殖器最大肿胀期的成年雌性（发情雌性）的群体中有更多雄性。此外，包含更多发情雌性的双性群体中有更多雄性。这些结果表明，黑猩猩的大型双性群体是由双重机制构成的。首先，处于发情期的成年雌性被由地位最高的雄性以及大量成年和青少年雄性组成的群体所吸引。其次，原本不属于群体的成年和青少年雄性被发情雌性吸引并加入其中。因此，在坦桑尼亚的马哈勒山脉国家公园，黑猩猩的双性群体可被描述为“繁殖群体”。
