Understanding how habitat quality, insect abundance and aquatic subsidies impact population change in a rapidly declining bird

全球候鸟数量的下降是对世界生态系统的主要威胁。大量长途迁徙在温带繁殖区和热带越冬地之间穿梭，在大空间尺度上提供能量转移和生态系统服务。此外，鸟类数量趋势是环境变化的关键指标，因此迁徙数量的减少令科学家和政策制定者都感到担忧。移民特别容易受到环境变化的影响，因为他们的生命周期处于多个阶段，研究越来越多地将气候变化与他们的衰落联系在一起。然而，对气候的关注意味着环境变化的其他方面受到的关注要少得多。最近备受瞩目的研究报告称，世界各地的昆虫数量出现了灾难性的崩溃。虽然这些发现的概括性存在争议，但大多数研究人员都同意，关键群体的迅速减少对生态系统功能具有令人担忧的影响。例如，昆虫是许多候鸟饮食中的关键组成部分，但昆虫的数量趋势与它们的鸟类捕食者之间的相互作用还没有得到很好的理解。斑点苍蝇是英国衰退最快的鸟类之一，但其根本原因尚不清楚。作为一种专性食虫者，该物种是环境健康的重要指标，也是研究昆虫数量下降与候鸟数量下降之间联系的理想模型。针对这种“优先物种”的生物多样性行动计划突出了在繁殖、生态和栖息地利用方面的知识差距。该项目通过将长期数据分析与实地考察、空间分析、前沿实验室技术和种群模型相结合来解决这些问题，以便：(1)调查栖息地变化和无脊椎动物丰度对国家种群趋势的影响；(2)确定栖息地质量和食物供应如何影响当地种群的繁殖成功；以及(3)利用(1)和(2)的结果建立种群变化的综合模型。

Global declines in migrant bird populations are a major threat to the world's ecosystems. Long-distance migrants travel in vast numbers between temperate breeding regions and tropical wintering grounds, providing energy transfer and ecosystem services at large spatial scales. Furthermore, avian population trends are key indicators of environmental change, so migrant declines are concerning for scientists and policymakers alike. Migrants are particularly susceptible to environmental change because of their multistage lifecycle, and research increasingly implicates climate change in their decline. However, focusing on the climate has meant that other aspects of environmental change have received far less attention.Recent high profile studies have reported a catastrophic collapse in insect numbers around the world. While the generality of these findings is contentious, most researchers agree that rapid declines of key groups have worrying implications for ecosystem functioning. For example, insects are a critical component of the diet of many migrant birds, yet the interplay between the population trends of insects and their avian predators is poorly understood.The spotted flycatcher Muscicapa striata is one of the UK's most rapidly declining birds, but the underlying causes are unclear. As an obligate insectivore, this species is an important indicator of environmental health and an ideal model for studying the link between declines in insects and migrant birds. The Biodiversity Action Plan for this 'Priority Species' highlights knowledge gaps regarding breeding ecology and habitat use. This project addresses these by combining analyses of long-term data with fieldwork, spatial analysis, cutting-edge laboratory techniques and population modelling in order to: (1) investigate the impact of habitat change and invertebrate abundance on national population trends; (2) determine how habitat quality and food availability affect breeding success in a local population; and (3) use the results from (1) and (2) to develop an integrated model of population change.