The sooty mangabey (Cercocebus atys) practices year-round durophagy. A large part of the C. atys diet consists of the oily nut of Sacoglottis gabonensis, which is accessed by post-canine crushing of the hard, protective seed coat. During a typical foraging bout, some seeds are discarded after initial crushing attempts using isometric biting, but the reason mangabeys reject some seeds and break into others is unclear. Although C. atys is sexually dimorphic, little is known about whether differences between males and females affect the selectivity of mechanically protected foods. We studied C. atys feeding on S. gabonensis in the Taï National Park, Côte d'Ivoire, in July and August 2016. Nuts discarded after an initial crushing attempt were collected and their hardness measured using a Shore D durometer. Measurements were taken in the region of the nut where monkeys attempted to crush it. Hardness values of nuts rejected by adult male (n = 79) and adult female (n = 104) C. atys were compared to those of a control assemblage of nuts collected randomly on the forest floor (n = 69). Nuts rejected by either sex do not differ statistically from the random sample; however, they do differ from each other, with females rejecting harder nuts. This suggests that males are more effective at broaching harder seed husks, and discard seeds based on other factors.

中文翻译：

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黑头白眉猴（Cercocebus atys）的种子选择因性别而异

乌黑的白眉猴 (Cercocebus atys) 全年都在进行食肉。C. atys 饮食的很大一部分由 Sacoglottis gabonensis 的油性坚果组成，通过犬类后压碎坚硬的保护性种皮获得。在典型的觅食回合中，一些种子在使用等距咬合进行初步压碎尝试后会被丢弃，但白眉猴拒绝某些种子并闯入其他种子的原因尚不清楚。尽管 C. atys 是两性异形的，但人们对雄性和雌性之间的差异是否会影响机械保护食物的选择性知之甚少。我们于 2016 年 7 月和 8 月在科特迪瓦的塔伊国家公园研究了以 S. gabonensis 为食的 C. atys。收集了初次压碎尝试后丢弃的坚果，并使用 Shore D 硬度计测量了它们的硬度。在猴子试图压碎坚果的区域进行了测量。被成年男性（n = 79）和成年女性（n = 104）拒绝的坚果的硬度值与在森林地面上随机收集的对照坚果组合（n = 69）进行了比较。任一性别拒绝的坚果与随机样本在统计学上没有差异；然而，它们确实彼此不同，雌性拒绝更硬的坚果。这表明雄性在拉削较硬的种子壳方面更有效，并根据其他因素丢弃种子。任一性别拒绝的坚果与随机样本在统计学上没有差异；然而，它们确实彼此不同，雌性拒绝更硬的坚果。这表明雄性在拉削较硬的种子壳方面更有效，并根据其他因素丢弃种子。任一性别拒绝的坚果与随机样本在统计学上没有差异；然而，它们确实彼此不同，雌性拒绝更硬的坚果。这表明雄性在拉削较硬的种子壳方面更有效，并根据其他因素丢弃种子。