Later onset of breeding in an apex predator in response to climate change: causes and consequences

气候变化是21世纪野生动物种群和生物多样性面临的最根本风险之一。长期研究对于深入了解这种变化的原因和后果至关重要，尤其是在顶级捕食者中。在普通秃鹰Buteo Buteo的种群中，尽管气温升高，但在1990年至2010年期间，繁殖的平均开始时间已经向后推迟了一个多星期。我们建议探索哪种机制可能最好地解释这一矛盾的结果，并阐明生物对气候变化反应的复杂性。有了涵盖繁殖时间、繁殖成功率、个体生活史和健康状况的数据，可以测试六个主要假设。是适应性进化反应、表型可塑性、气候选择压力的放松、个体条件的恶化，还是年龄结构或羽毛分布的变化来解释后来的繁殖？最可能的机制是如何与生命史相互作用来影响种群动态的？在22年的时间里，汇编了500多部生活史，记录了不同群体在应对气候变化时的权衡变化。人口动态将采用时间序列分析和以天气为协变量的矩阵模型进行建模，以找到影响人口增长和波动的关键因素。结果将推广到1975年以来在同一研究区域研究的另一种顶端捕食者——苍鹰。使用两个物种和同一地区，可以发现人口增长和波动的一般相关性。利用目前115个持续时间至少为10年的时间序列，利用独特的大陆尺度兀鹰种群动态元数据集进一步推广研究结果。

Climate change poses one of the most fundamental risks to wildlife populations and biodiversity in the 21st century. Long-term studies are vital to obtain a deeper understanding of the causes and consequences of this change, especially in apex predators. In a population of common buzzards Buteo buteo, average onset of breeding has shifted backwards by over a week over the time period 1990-2010, despite warmer temperatures. We propose to explore which mechanism might best explain this paradoxical result and elucidate the complexity of organisms’ responses to climate change. With data covering breeding times, reproductive success, life histories of individuals and fitness, six major hypotheses can be tested. Is later breeding explained by an adaptive evolutionary response, phenotypic plasticity, relaxed selection pressure by climate, worsening of individual condition, or changes in the age structure or plumage distribution? How does the most likely mechanism interact with the life history to influence population dynamics? Over 500 life histories compiled across 22 years will document shifts in trade-offs between cohorts in response to climate change. Population dynamics will be modelled with time series analyses and matrix models with weather as a covariate to find key factors influencing population growth and fluctuations. Results will be generalized to another apex predator, the goshawk Accipiter gentilis which has been studied in the same study area since 1975. Using two species and the same area, allows general correlates of population growth and fluctuations to be found. Results will be further generalized using a unique continental scale metadata set on common buzzard population dynamics with currently 115 time series of at least 10 year duration.