Wrangham R W, Smuts B B
J Reprod Fertil Suppl. 1980;Suppl 28:13-31.
All-day observations of focal individuals were analysed to compare grouping and ranging patterns and the proportion of time spent feeding by females and males; sexually receptive females were not included. Females spent most of their time alone, whereas males spent most of their time in parties with other males. Females travelled shorter distances than males, and spent their time in smaller core areas: when they joined parties, however, they often travelled outside their normal core areas. Grouping and ranging patterns appear to be related to foraging strategies in different ways in each sex. Females often joined parties for a short time only (< 1 1/2 h), apparently at rich food sources. Males tended to stay for longer, even though they then spent less time feeding than when alone. Spending all day in a party was associated with reduced feeding time for both sexes, but on these days ranging patterns differed between the sexes because males, but not females, travelled further when in parties. The results support the idea that the form of the chimpanzee social system is determined by the interaction of two different strategies: females attempt to forage so as to maximize net energy intake, while males sacrifice an optimal foraging strategy for the sake of reproductive competition.
对重点个体进行全天观察，以比较其群体形成和活动范围模式，以及雌性和雄性用于进食的时间比例；未纳入处于发情期的雌性。雌性大部分时间独自活动，而雄性大部分时间与其他雄性聚在一起。雌性的活动距离比雄性短，且活动范围较小：然而，当它们加入群体时，往往会离开其正常的核心活动区域。群体形成和活动范围模式在两性中似乎以不同方式与觅食策略相关。雌性通常仅在食物丰富的地方短时间（<1.5小时）加入群体。雄性倾向于停留更长时间，尽管它们此时用于进食的时间比独自活动时少。在群体中度过一整天会导致两性的进食时间减少，但在这些日子里，两性的活动范围模式有所不同，因为雄性在群体中时活动距离更远，而雌性并非如此。这些结果支持了这样一种观点，即黑猩猩社会系统的形式是由两种不同策略的相互作用决定的：雌性试图通过觅食来使净能量摄入最大化，而雄性为了生殖竞争而牺牲最优觅食策略。
