From April 2009 to January 2010, we conducted surveys to determine the current status of water birds at Yamdrok Lake in Tibet, China. During the survey, visual search was the main method used. Twenty-four sites were selected around the lake, based on water bird distribution and accessibility by road. Once flocks were identified, observers approached the birds close enough on foot for identification and counting. The winter home ranges of two individuals of the bar-headed goose Anser indicus were by kernel analysis to determine the sites that were important for wintering of the bar-headed goose. A total 31,044 water birds were tallied, belonging to 32 species, 10 families, and 6 orders. Birds of the family Anatidae and gulls were predominant among the species counted, with proportions of 73.9% and 19.1%, respectively. The migration peaks of water birds at Yamdrok Lake occur in spring and autumn. Bar-headed geese and brown-headed gulls (Larus brunnicephalus), along with a small population of black-necked cranes (Grus nigricollis), occupied the major parts of the breeding grounds in summer, while the red-crested Pochard (Rhodonessa rufina) was the dominant species in winter, often resting in areas where ice was melting. The results also showed that population numbers of the bar-headed goose varied with season. Thus, its numbers increased slightly in spring, resulting from migration to the lake from southern populations, such as those from India. During the breeding period, over 2000 breeding individuals were recorded nesting at the bird island in the southwest part of the lake, and geese were seldom found in other areas. During molting, and with pressure from increasing populations, geese with their chicks were often seen foraging in the marshes and other wetlands along the edges of lakes. The population numbers decreased in autumn as many geese departed for their wintering sites. In winter, because of arrivals at the lake from northern areas such as Qinghai Lake and Qiantang, Tibet, the goose population increased again, and they were often found in the marshes and wetlands of the lake, where abundant food was available. According to the results from satellite tracking, Yamdrok Lake is an important wintering and breeding site for the bar-headed goose at Qinghai Lake, and the geese were often found in the marshes at the western end of the lake and the delta in the southern lake. In addition, a close link between Yamdrok Lake and the Yarlung Zangbo River benefitted the movement of the bar-headed goose between these two sites. As a result, it is reasonable to suggest that the lake should be seen as an important site at which to conduct surveillance in southern Tibet for avian influenza.