中华秋沙鸭中途停歇地的质量及迁徙对策

Since last century, climate change and economic development have resulted in continuous habitat degradation and loss for avian species. Understanding the impact of stopover sites quality on bird migration is a critical issue in the study of bird conservation. The Scaly-sided Merganser (Mergus squamatus) is recognized as the globally endangered species by the IUCN Redlist, which is breeding in a narrow region in Northeast China and Russian Far East but wintering in vast area of Southern China. Dam construction, sand dredging, illegal fishing and river pollution represent the major threats on stopover sites and wintering grounds which consequently cause profound impact on the population decline of Scaly-sided Merganser. Understanding the stopover sites quality and the relevant migration strategies taken by Scaly-sided Merganser is critical to protect this species...This study selects the biggest breeding population of the Scaly-sided Merganser in China as the study target. We employ satellite tracking, ground monitoring and GIS analysis to precisely figure out the migration routes, migration timing and stopover sites utilization pattern, and consequently reveal the migration strategies of Scaly-sided Merganser. Field sampling and multivariate statistical analysis will be applied to quantitatively reveal the key habitat factors at stopover sites and develop the habitat suitability index model. The model will subsequently be used to assess the stopover sites quality on the migration route. Finally, Network Analysis Model will be employed to simulate potential migration routes which are used to evaluate the impact of habitat quality on migration strategies and determine key stopover sites with high conservation priority. The results would provide the basis for restoring and managing the population and habitat of Scaly-sided Merganser, and contribute to understanding the ecological adaption of migration strategies for endangered species under environment pressure.

在气候变化和经济发展导致鸟类栖息地持续退化和丧失的背景下，评估中途停歇地的质量对鸟类迁徙的影响，是鸟类保护和研究的热点问题。中华秋沙鸭（Mergus squamatus）是全球濒危物种，其种群正面临着迁徙路线上栖息地丧失的严重威胁。本项目选择我国最大的中华秋沙鸭繁殖种群，通过卫星跟踪、实地监测和GIS分析，精确揭示其迁徙路线、迁徙的时间选择和对中途停歇地的利用模式，综合分析中华秋沙鸭的迁徙对策；通过调查取样和多元统计分析，定量分析影响中华秋沙鸭对中途停歇地选择的关键栖息地变量，构建中途停歇地的栖息地适宜度指数模型，并开展栖息地质量评估；通过模型分析，评估中途停歇地质量对迁徙对策的影响，并筛选出需要优先保护的中途停歇地。研究结果为迁徙路线尺度上中华秋沙鸭种群及栖息地保护管理提供科学依据，为揭示环境压力下濒危鸟类迁徙对策的生态适应机制提供参考资料。

中华秋沙鸭（Mergus squamatus）是全球濒危物种，其种群正面临着迁徙路线上栖息地丧失的严重威胁。掌握其迁徙路线、中途停歇地的质量及迁徙策略，对于该物种的保护至关重要。长白山是中华秋沙鸭在我国的主要繁殖地，其沿河营巢密度为0.65±0.17巢/km（n=4）。首次发现中华秋沙鸭存在种内巢寄生现象，其原因可能与巢址资源有限及巢址密度过高相关。河道中家庭群的密度为0.39±0.05群/km（n=4），平均窝雏数为8.5±2.8（n=37）；23.8%±4.3%的家庭群存在窝雏合并现象，这可能与亲鸟之间对育雏栖息地的竞争以及雏鸟被捕食风险的稀释效应相关。中华秋沙鸭的成年雄鸟在雌鸟开始孵卵后离开繁殖地，向北反向进行换羽迁徙，迁徙距离达1035±713km（n=4）。换羽主要发生在7-8月份，换羽期活动区为6.1±1.2km2（n=4）。中华秋沙鸭秋季迁徙始于10月29日，迁徙时间42.7±16.0天。跨越渤海迁徙，主要至华中及华南地区越冬，迁徙距离1600~4000km不等。春季迁徙始于3月30日，迁徙时间15.0±9.9天。春季北迁速度显著快于秋季南迁速度，可能是为了尽快到达繁殖地抢占有限且适宜的巢洞资源。加之北迁的停歇地数量（2个）比南迁少（6个），初步判断中华秋沙鸭秋季南迁采用“能耗最小”的迁徙策略，而春季北迁采用“时间最短”的迁徙策略。中途停歇地选择的关键因子包括石滩或沙洲的面积、水体的透明度以及环境的干扰程度。为促进迁徙路线水平上中华秋沙鸭的保护，我们建议规范中华秋沙鸭人工巢箱的制作和悬挂以及生态摄影行为，减少人为干扰；在水电站修建鱼类洄游通道，提高中华秋沙鸭的食物丰富度；对非法下网捕鱼、河道采砂加强管控和监督，减少中华秋沙鸭的威胁，提高觅食地的质量。