Abstract: The Tibetan gazelle (Procapra picticaudata) is an endangered species inhabiting theQinghai-Tibetan Plateau. From October 2002 to December 2003, we observed 924 groups (3643 individuals) of Tibetan gazelles in Hoh Xil region. These groups could be classified into five types.Female groups (525) were the major type, accounting for 56.8%. Solitary gazelle (a special group type), male groups, mother-calf groups and mixed groups made up 26.1%, 11.0%, 3.0% and 3.0%, respectively. Group size ranged from one to 17 individuals. Groups of 2-10 individuals, solitary gazelle groups and larger groups (>10 individuals) accounted for 70.0%, 26.1% and 3.9%, respectively. 72.9% of gazelles were observed in group with sizes of 2-8 individuals, while 20.5% were observed in group sizes > 8 and 6.6% were solitary. A chi-square test showed that the frequencies of individuals in different group sizes were significantly different (P<0.001). Group sizes varied significantly among different group types (Kruskal-Wallis H test,P<0.001). There were significantly more males (68.1%) than females (P<0.001) in solitary groups. To sum up, female group was the main group type of Tibetan gazelles, and the optimal group size was 2-8 individuals.

Key words: distribution, fluctuation, microorganism