The group pattern of Marco Polo sheep in the Chinese Pamir plateau

Abstract

The study of group patterns in ungulates is very important, since grouping is a basic element of social organization. However, the behavior of Marco Polo sheep has been rarely reported because this argali subspecies lives in high-elevated, hard-to-reach areas. Therefore, in this study, we investigated the group size and group composition of Marco Polo sheep in the Pamir plateau. We found that though small groups (1–10 individuals) were the most numerous, the greatest number of argali formed mid-sized groups of 6–20 individuals, which was significantly larger compared to group sizes in other argali subspecies. This preference in Marco Polo sheep is likely related to their specific habitat, which is located on high-elevated plateaus with the least rugged and most open terrain, where staying in larger groups is the most effective strategy for survival. Regarding group composition, female groups were the most often registered, followed by male groups and mixed-sex groups. Mixed-sex groups were found more often during rutting season, slightly less often in winter and very rarely in other seasons, when most adult males and females were segregated into single-sex groups. Mixed-sex groups generally had the largest number of animals, which changed insignificantly over seasons, while female groups and male groups varied significantly and were closely correlated to the yearly breeding cycle and the availability and quality of their food supply. Marco Polo sheep formed larger groups as an effective antipredator strategy in seasons when forage amounts allowed them to do so, though human activities also had a significant impact on group patterns, forcing out wild sheep to aggregate on remnants of suitable pastures.