栖息地破碎化与退化对栗斑腹鹀繁殖对策选择的影响

Habitat loss and degradation are the greatest threats on biodiversity worldwide. However, the effects of grassland loss and degradation on different species are different, resident species with narrow distribution and population sizes are vulnerable to be affected. Jankowski’s Bunting (Emberiza jankowskii) is a typical grassland bird, it distributes narrowly and is undergoing reduction drastically, declining rapidly and suffering low reproduction. The status of the species has received attention widely. The species has been listed as Endangered by IUCN since 2010. By targeting the primary ecological pressures that the species faced, the project aims to reveal its ecological requirements, to reveal the internal and external mechanisms causing the species being endangered by developing study on its selection on fragmented and degraded habitats, on the risk of nest being predation by predators, on parasitism by cuckoos and inbreed in fragment and degraded habitats, and on breeding strategies under different ecological pressures. By doing so, we could know the ability to adapt to habitat fragmentation and degradation, and cound evaluate the population trend and the risk of being extinction in the bunting, and could provide scientific foundations for making strategies and measures to restore and manage habitats, to establish nature reserve.

栖息地丧失和退化是对世界范围内物种多样性的最主要的威胁。草原生境丧失和退化对不同物种的影响并非等同，对分布区狭窄和数量较小的留鸟种群影响最为显著。栗斑腹鹀为典型草原鸟类，分布区狭窄并急剧萎缩、繁殖成功率低、种群持续下降，其种群现状已受到国内外高度关注，国际鸟盟（IUCN）2010 年将其濒危等级由易危调至濒危。针对栗斑腹鹀种群生存所面临的主要压力，本项目拟通过开展栗斑腹鹀对栖息地破碎化和退化生境的选择利用、栖息地破碎化和生境退化与栗斑腹鹀的巢捕食和寄生及近亲交配风险分析、不同生态压力下栗斑腹鹀繁殖对策选择等研究，揭示其生态需求，从宏观和微观层面分析栗斑腹鹀濒危的内在和外在机制，探讨栗斑腹鹀对栖息地破碎化和退化的生存适应能力，为预测种群动态变化与灭绝风险，制定栗斑腹鹀的栖息地管理与恢复、建立保护区或保护小区等管理措施和保护对策提供重要的科学依据。

项目组对栗斑腹鹀历史、现存和潜在分布区进行了全面调查，确认栗斑腹鹀已从除大岗、西尔根和图牧吉外的历史分布区内消失，但在内蒙古中东部发现13个新的繁殖分布区，繁殖种群数量约1万只。尽管种群遗传多样性研究结果表明现存栗斑腹鹀种群仍保留较高的遗传多样性，然而种群正受到栖息地破碎化和退化的严重威胁。栖息地破碎化导致蛇和草原鼠等天敌对栗斑腹鹀卵和雏鸟的捕食增加，大杜鹃的巢寄生和种间竞争等因素导致栗斑腹鹀繁殖成功率较低，局域栗斑腹鹀种群存在近亲繁殖现象。此外，大气中的重金属污染物也可能对栗斑腹鹀的繁殖成功率产生负面影响。对驱动草原鸟类丰度和共存的非生物和生物因素研究发现：气候、景观和草原生境预测因子并非构成鸟类群落结构的唯一要素；栗斑腹鹀可以作为草原营开放巢鸟类的指示生物。另外，项目组初步分析了繁殖期栗斑腹鹀成鸟与雏鸟的肠道微生物组成结构，发现不同雏鸟年龄组间α多样性和丰富度无显著差异，雏鸟和成鸟间物种丰富度及多样性上也无显著差异。项目所获研究成果：根据世界自然保护联盟红色名录类别和标准，中国境内的栗斑腹鹀仍符合B2ab的濒危物种标准，研究结果可为栗斑腹鹀的保护提供科学依据，建议将内蒙古地区内的栗斑腹鹀作为一个大的保护单元进行保护，并对扎鲁特旗和阿鲁科尔沁旗内繁殖种群进行重点保护，同时需建立多个栗斑腹鹀保护小区；证实了栖息地破碎化和退化是导致栗斑腹鹀个体数量减少的主要原因；有助于加深研究者对非生物过程和生物过程是如何相互影响鸟类群落组成的理解。依托该项目研究的研究结果发表论文10篇，其中SCI论文6篇，核心期刊论文4篇，软件著作权3项。培养博士研究生3名，硕士研究生5名，其中已毕业研究生2名。