Density of Japanese Macaque (Macaca fuscata yakui) Males Ranging Alone: Seasonal and Regional Variation in Male Cohesiveness with the Group

Abstract

Abstract. We conducted point censuses in Yakushima island to estimate the density of Japanese macaque (Macaca fuscata yakui) males ranging alone, focusing on its vegetational, seasonal, and regional variation. In highland areas, the detection frequency of males ranging alone did not differ among different types of vegetation, despite the latter's effect on overall population density. The detection frequency of males ranging alone in the mating season was a third of that in the non-mating season. In the mating season, males exhibit strong cohesiveness with a group, probably in search of resident estrous females. Outside of the mating season, we detected 25% fewer males ranging alone in lowland areas, which have high population densities and strong inter-group competition, than in highland areas. The absolute density of males ranging alone was estimated to be 1.2–5.7 individuals/km2. Meanwhile, the group and population densities were 1.25/km2 and 19.3/km2, respectively. A considerable number of males theref...