From November to December 2014 and in April 2015,the Castor fiber birulai(Xinjiang beaver) lodge site selection and characteristics in the cold and early warm seasons in the Ulungur watershed of Xinjiang were investigated by line transect and plot sampling methods.In the cold and early warm seasons,a total of 160 and 158 lodge sites were found respectively,which indicated that there were 160 and 158 beaver families.There were 61 beaver families that built lodges on the ground,which accounted for 38.13% of lodge sites in the cold season and 38.61% in the early warm season.Mean lodge lengths were (2.54±1.69) m,while the widths were (1.68±0.91) m,and their heights were (0.54±0.32) m.Compared with that of the cold season,the C.f.birulai lodge site selections of the early warm season had the following characteristics:the nearby river was wider,deeper and bigger,its bank slope was steeper,and the surrounding vegetation canopy was larger.The vegetation canopy was affected by seasonal weather changes,which did not have significant effects on other habitat factors.Illustrated by the case of the cold season,after 17 environmental variables possibly pertaining to beaver lodge site selection were measured and analyzed,the results showed that the Xinjiang beaver lodge sites were mainly located at high-elevation (>1000m) near water areas with width and area suitable for living,with characteristics including high river banks (>1.0m),steep slopes (>75°),and deep water (>1.0m).The environment of beaver lodge sites was covert,where vegetation characteristics included high crown and tree density,and low density and height of shrubs.The beaver lodge sites were usually located on the opposite river bank of nearby human roads and houses.Furthermore,the vast majority of beaver lodge sites were in high-density willow forests and near a food cache.The beaver lodge site selections are heavily influenced by human activities;hence,measures should be taken immediately to protect the Xinjiang beaver,such as seeking other fit habitats for beavers to live in based on the stated selection characteristics,reducing the number of human dams in the Ulungur watershed,or building migration channels for beavers near human dams,thereby strengthening the protection and management of C.f.birulai in its distribution area.