中文摘要：

2014年11—12月和2015年4月，采用样方法对新疆乌伦古河流域冷季和暖季早期蒙新河狸（Castor fiber birulai）巢穴特征和巢址生境选择进行了调查研究。确定冷季160个蒙新河狸巢穴和暖季早期158个蒙新河狸巢穴，其中61个地面巢平均长（2．54±1．69）m，宽（1．68±0．91）m，高（0．54±0．32）m。与冷季相比，暖季早期蒙新河狸利用的巢穴生境具有河宽、水域面积、水深和植物郁闭度较大，河岸坡度较小的特征，是由季节更替导致的温度等气候变化引起的．而在其他生态因子选择上无差异（P〉0．05）。以冷季为例，蒙新河狸巢址生境选择特征表现为：（1）地理分布因子：海拔〉1000m．临近水域河岸〉1．Om、坡度〉75。、水深〉1．Om、河面宽度和面积适中；（2）隐蔽因子：巢穴隐蔽级较高，附近的植物特征（郁闭度高，乔木密度大、灌木密度低以及高度低）也辅助实现了较好的隐蔽性；（3）干扰因子：巢穴位置选择最近公路或居民点的河流异侧；（4）食物因子：巢穴多选择在密度较高的柳树林中，且距离冬季食物堆较近。建议：寻找适合蒙新河狸生存的其他潜在生境；减少在蒙新河狸生活流域修建水坝，或者在其附近修建蒙新河狸迁徙通道；加强蒙新河狸分布区的保护管理。

英文摘要：

Abstract： 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 （〉l.0m）, steep slopes （〉75°）, and deep water （〉l.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