Do differences in ecological conditions influence grouping behaviour in a solitary ungulate, the Japanese serow?

One aim of animal behaviour research is to explain why animals live in groups. The grouping behaviour of solitary mammals is important for understanding the ecological factors promoting the evolution of sociality. We present field data of Japanese serow, a primitive solitary ungulate, in forest and alpine meadow habitats. We found no differences in group size of all age–sex classes between the forest and alpine meadow habitats, and both populations were mainly solitary. The current findings suggest that group size in the serow is not affected by ecological conditions, including habitat structure, forage abundance, and population density. However, female associations involving up to three females occurred in the alpine meadow habitat throughout the year, whereas such groupings were not observed in the forest habitat. This finding suggests that abundant food supply in the alpine meadow promoted female associations by decreasing the cost of food resource competition.