The Group Characteristics Of Blue Sheep (Pseudois Nayaur) In Helan Mountain

Group living is a social behavior of animals. The research on the group characteristics of a certain species in different areas and different seasons would help to understand the social behavior and aggregation mechanism. Blue sheep (Pseudois nayaur) is the second grade Chinese protected wildlife which is classified into Pseudois genus, Caprinae subfamily, Bovidae family. Blue sheep is one of the most abundant wildlife of Tibet plateau. Its population in Helan Mountain has been increasing in recent twenty years.The study was carried out from November to December in 2003, from October to December in 2004, from May to October in 2005 in Ningxia Helan Mountain National Nature Reserve and Inner Mongolia Helan Mountain National Nature Reserve. Focused on the characteristics of blue sheep in Helan Mountain, the study adopted line transects to make observation with the help of telescopes, GPS and digital camera. The findings are as follows:The average group size of different group types, percent of different group types, group size of female group, group size of mother-young group and group size of mixed group were seasonally significantly different (P < 0.05), while group size of male group and male-female group had no significant difference. The seasonal changed overall resource availability and periodicity of rut constitute the primary reasons for those changes. The age-sex ratio changed seasonally (P < 0.05), whether the male/female ratio, young/female ratio or yearling/female ratio. The different tolerance abilities of different age-sex blue sheep and periodicity of rut may be responsible for those age-sex ratio changes.The group size was of no significant differences (P < 0.05) among the male group, female group, male-female group, mixed group, and mother-young group in pre-rut and main rut period. The group type compositions were significantly different (P < 0.05) in pre-rut and main rut period. Both of the distributions of male and female blue sheep in different group types were significantly different (P < 0.05) in pre-rut and main rut period. Whenever possible, the male blue sheep were classified into four age classes: I (2.5~3.5a), II(4.5~5.5a), III(6.5~8.5a) and IV(= 9.5a). The distribution of male blue sheep of each age class in male group, male-female group, mixed group and solitary was significantly different (P < 0.05).