Impact of Non-Native Birds on Native Ecosystems: A Global Analysis

Introduction and naturalization of non-native species is one of the most important threats to global biodiversity. Birds have been widely introduced worldwide, but their impacts on populations, communities, and ecosystems have not received as much attention as those of other groups. This work is a global synthesis of the impact of nonnative birds on native ecosystems to determine (1) what groups, impacts, and locations have been best studied; (2) which taxonomic groups and which impacts have greatest effects on ecosystems, (3) how important are bird impacts at the community and ecosystem levels, and (4) what are the known benefits of nonnative birds to natural ecosystems. We conducted an extensive literature search that yielded 148 articles covering 39 species belonging to 18 families -18% of all known naturalized species. Studies were classified according to where they were conducted: Africa, Asia, Australasia, Europe, North America, South America, Islands of the Indian, of the Pacific, and of the Atlantic Ocean. Seven types of impact on native ecosystems were evaluated: competition, disease transmission, chemical, physical, or structural impact on ecosystem, grazing/ herbivory/ browsing, hybridization, predation, and interaction with other non-native species. Hybridization and disease transmission were the most important impacts, affecting the population and community levels. Ecosystem-level impacts, such as structural and chemical impacts were detected. Seven species were found to have positive impacts aside from negative ones. We provide suggestions for future studies focused on mechanisms of impact, regions, and understudied taxonomic groups.

非本土物种的引入与归化（naturalization）是全球生物多样性（biodiversity）面临的最重要威胁之一。鸟类已在全球范围内被广泛引入，但相较于其他生物类群，其对种群（population）、群落（community）与生态系统（ecosystem）的影响并未受到同等程度的关注。本研究针对非本土鸟类对本土生态系统的影响开展全球综合分析，旨在明确四个核心研究问题：（1）哪些类群、影响类型与研究区域得到了最为充分的研究；（2）哪些分类类群与影响类型对生态系统的影响最为显著；（3）鸟类影响在群落与生态系统层面的重要性如何；（4）非本土鸟类对自然生态系统存在哪些已知的益处。我们开展了大规模文献检索，最终得到148篇符合要求的文献，涵盖18个科的39个物种，占所有已知归化非本土鸟类物种总数的18%。研究按开展区域进行分类：非洲、亚洲、大洋洲（Australasia）、欧洲、北美洲、南美洲、印度洋岛屿、太平洋岛屿与大西洋岛屿。本研究评估了针对本土生态系统的七类影响：竞争、疾病传播、对生态系统的化学、物理或结构影响、放牧（grazing）、植食（herbivory）与啃食（browsing）、杂交、捕食，以及与其他非本土物种的相互作用。其中，杂交与疾病传播是最为重要的影响类型，可作用于种群与群落层面。研究同时检测到了生态系统层面的影响，例如结构与化学影响。另有7个物种被发现可产生除负面影响之外的正向影响。最后，我们针对未来研究提出建议，应聚焦于影响机制、研究区域以及尚未得到充分研究的分类类群。