Over 6 million yaks (Bos grunniens) are grazed in the alpine rangelands of the eastern Tibetan Plateau in Qinghai Province, China. Degradation of rangelands has been caused by increased numbers of domestic animals following the rise of the human population. In our previous study in northern and southern sites of Tibetan Plateau in Qinghai Province from 2003 to 2006, behavior of yaks and chemical composition of the faeces (Hasegawa et al. 2006; Hasegawa et al. 2008) and vegetation (Li et al. 2006; Song et al. 2006) were investigated and compared between the two sites, and it was suggested that the material circulation was lower and deterioration of rangeland was greater in the former than in the latter. In this study, behavioral observations of yaks in alpine rangeland of Yushu National Ranch from 2004 to 2012 were carried out to estimate the change of rangeland condition in the southern site of Tibetan Plateau
