津巴布韦奇马尼马尼人工松林中狒狒分布型和结群大小与树木剥皮的关系

本研究调查了人工松林中狒狒结群大小和家区面积与树木剥皮率的关系。于2003年9月至2004年8月间每月对每个狒狒结群进行5天观察,采用足迹计数法统计狒狒结群大小,对不同结群狒狒家区内具有新旧剥皮的树木数进行统计,以方差分析和回归分析狒狒结群大小和家区面积与树木剥皮之间的关系。结果表明:定居和访问松林的狒狒结群分布型不受结群和家区大小的影响而与季节有关。树木剥皮与狒狒结群大小和家区面积均无相关性,特别是雨季更是如此,揭示狒狒对树木剥皮不是对食物和水源短缺的反应。树木剥皮具有很大的月份间变异,与狒狒群定居和访问利用松林亦无相关。树木剥皮率与狒狒结群大小的关系说明树木剥皮是由于狒狒结群中少数个体的偶然剥皮行为造成的。     

Female Defensibility in a Small Troops of Japanese Macaques vis-à-vis Nontroop Males and Copulation on the Periphery of the Troop

I provide data compiled over 4 yr on the mating behavior in small troops of wild Japanese macaques on Yakushima Island. The key parameters are the number of sexually receptive females, the number of nontroop males (NTMs), and copulation on the periphery of the troop. I analyzed the following aspects: 1) changes in the proportion of copulation with high-ranking males (HRMs) and NTMs, 2) variations in factors such as fluctuation in the number of sexually receptive females and troop males and their effects on the number of visiting NTMs, 3) the effect of attempted interruption of mounting series by other males, and 4) some aspects of copulation on the periphery of the troop. Throughout the study, 56% of the total number of females mated most frequently with the α-male in a single mating season. However, the relative mating success of HRMs varied over the years and between individuals. The number of visiting NTMs varied depending on the number of receptive females and troop males. Females tended to mate with the NTMs when they appeared around their troops. The direct effect of interruption of the mounting series by other males is equivocal. The females mated with the low-ranking males (LRMs) and NTMs on the periphery of the troop, which increased the possibility of mounting series ending with ejaculation. Females actively sought opportunities for copulation on the periphery of the troop by moving there or initiating close proximity with LRMs and NTMs there. On Yakushima Island, the mating success of HRMs was not always as high as that predicted by the priority of access model. The injury status of the HRM, the number of visiting NTMs, and female choice are all considered to influence a male’s mating success.