Spatial organization and mating behavior of the Japanese serow under a low population density

Abstract

Abstract In high-density populations, the adults of the Japanese serow (Capricornis crispus) defend their home ranges against same-sex intruders, and a male’s territory typically overlaps with those of one to three females. We examined the spatial organization and mating behavior of the species in a low-density population by direct observation and radio-tracking over a 4-year period. The home range size of both males and females was more than 4 times larger than that reported in high-density populations. Adult females had ranges that overlapped little, even though they were never observed in agonistic interaction. In contrast, adult males had ranges that overlapped largely except in their core areas, and appeared to be tolerant on encounters, suggesting they did not defend their whole range as a territory. Although males’ ranges overlapped with multiple female ranges, males were only observed following a single female during the mating season. These findings suggest that males directly defended a female rather than a territory, and that the mating system is monogamous. The Japanese serow’s social organization would therefore vary according to ecological conditions.