西沙群岛主要岛屿鸟类和小型兽类群落调查研究

对海岛动物资源的本底调查和研究，可为更好地保护海洋和海岛生态系统提供重要的依据。2018年4月-2019年12月，利用样线法、铗夜法等对西沙群岛东岛、永兴岛等岛屿的鸟类、小型兽类资源进行了4次调查，结合历史记录数据对其物种组成和多样性变化进行了分析。调查共记录到小型兽类3种，臭鼩（Suncus murinus）见于林灌丛，褐家鼠（Rattus norvegicus）和黄胸鼠（R.flavipectus）见于房舍区；共记录到鸟类13目26科65种，其中国家Ⅱ级重点保护动物4种，新记录到鸟类29种；广布型鸟类34种，古北界鸟类20种，东洋界鸟类11种；冬候鸟28种，留鸟23种，旅鸟6种，夏候鸟5种，迷鸟3种；东岛鸟类物种数高于永兴岛，但多样性和均匀度均较低；雨季物种丰富度、多样性和均匀度均高于旱季；东岛为国家Ⅱ级重点保护动物红脚鲣鸟（Sula sula）中国唯一的繁殖地，应加强保护。与1974年和2005年报道的数据对比，本次调查记录的鸟类物种丰富度最高，留鸟物种数最多。结果反映西沙群岛小型兽类种类较少，主要分布在房舍区及其附近的林灌从；暗示小型兽类带入、扩散等可能与人为活动相关，其生态效应予以重视和长期监测。西沙群岛鸟类物种有丰富度较高、候鸟占比高、季节和年份间差异明显、留鸟物种数有所增加、为红脚鲣鸟唯一的繁殖地等特点。西沙群岛生态系统的完整性，对候鸟和留鸟的保护，尤其是红脚鲣鸟的保护十分重要，应予以重视。

Birds and small mammals in the main islands of Xisha Islands, China

The baseline survey and detailed analysis of wildlife resources constitute an important basis and guidance for better conservation of both marine and island ecosystems. Birds and small mammals of Xisha Islands were surveyed in Woody Island and Lincoln Island by using line transects from April 2018 to December 2019, species composition and diversity differences compared with historical records were analyzed. Three species of small mammals were recorded in this survey, of which, Suncus murinus was common in forests and shrubs, whereas Rattus norvegicus and R. flavipectus were usually trapped near houses and villages. A total of sixty-five bird species of thirteen orders, twenty-six families were recorded in Xisha Islands, including twenty-nine newly recorded species, four kinds of national second-class protected animals. In terms of faunal distribution, a total of thirty-four species of birds are widespread species, twenty are Palaearctic species, and eleven are Oriental species. In terms of residence type, twenty-eight species of birds are winter visitors, twenty-three are residents, six are passage migrants, five are summer visitors, and three are vagrant visitors. In Lincoln Island, bird species richness was higher than Woody Island, but the diversity index and evenness index were lower. Bird species richness, diversity index, and evenness index in the rainy season were higher than those in the dry season. Much attention should be paid to Lincoln Island because there are more than one hundred thousand individuals of Sula sula inhabited in the forest, which is its only large breeding ground in China. Compared with the historical data published in 1974 and 2005, species richness of birds, especially the resident bird species has increased. These results suggest that, in Xisha Islands, small mammals have a low species richness, mainly distributed in the forest and near houses, and their community dynamics are mainly related to human activities, the related ecological effects should be investigated continuously and paid attention to prevent rodent damage. The bird community in Xisha Islands is characterized by high species richness, a major proportion of migratory birds, great differences between islands, seasons, and years, an increasing species number of resident birds, and the only large breeding ground for S. sula in China. As an important transfer station of migratory birds and a key habitat of S. sula, the integrity of the ecosystem in Xisha Islands is crucial for both the migratory birds and resident birds, especially S. sula, local conservation should be given extra attention.