Ecologists widely acknowledge that a complex interplay of endogenous (density‐dependent) and exogenous (density‐independent) factors impact demographic processes. Individuals respond differently to those forces, ultimately shaping the dynamics of wild populations. Most comprehensive studies disentangling simultaneously the effects of density dependence, climate, and prey abundance while taking into account age structure were conducted in terrestrial ecosystems. However, studies on marine populations are lacking. Here we provide insight into the mechanisms affecting four vital rates of an apex Antarctic marine predator population, the South Polar Skua Catharacta maccormicki, by combining a nearly half‐century longitudinal time series of individual life histories and abundance data, with climatic and prey abundance covariates. Using multistate capture–mark–recapture models, we estimated age classes effects on survival, breeding, successful breeding with one or two chicks and successful breeding with two chicks probabilities, and assessed the different effects of population size, climate, and prey abundance on each age‐specific demographic parameter. We found evidence for strong age effects in the four vital rates studied. Vital rates at younger ages were lower than those of older age classes for all parameters. Results clearly evidenced direct and indirect influences of local climate (summer sea ice concentration), of available prey resources (penguins), and of intrinsic factors (size of the breeding population). More covariate effects were found on reproductive rates than on survival, and younger age classes were more sensitive than the older ones. Results from a deterministic age‐structured density‐dependent matrix population model indicated greater effects of prey abundance and sea ice concentration on the total population size than on the breeding population size. Both total population size and the number of breeders were strongly affected by low values of sea ice concentration. Overall, our results highlight the greater sensitivity of reproductive traits and of younger age classes to prey abundance, climate variability, and density dependence in a marine apex predator, with important consequences on the total population size but with limited effects on the breeding population size. We discuss the mechanisms by which climate variability, prey abundance, and population size may affect differentially age‐specific vital rates, and the potential population consequences of future environmental changes.

中文翻译：

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极地捕食者对气候及其猎物的人口和人口响应：对南极贼鸥的长期研究

生态学家广泛承认，内生（密度依赖）和外生（密度独立）因素之间复杂的相互作用会影响人口统计过程。个人对这些力量的反应不同，最终塑造了野生种群的动态。在陆地生态系统中，进行了最全面的研究，同时兼顾了密度依赖性，气候和猎物丰富度的影响，同时考虑了年龄结构。但是，缺乏关于海洋种群的研究。在这里，我们提供洞察力，以影响影响南极先例海洋掠食者南极贼鸥Catharacta maccormicki的四个生命率的机制，通过将近半个世纪的个人生活史和丰富度数据的纵向时间序列与气候和猎物丰富度协变量结合起来。使用多状态捕获-标记-捕获模型，我们估计了年龄类别对生存，繁殖，一只或两只雏鸡成功繁殖以及两只雏鸡概率成功繁殖的影响，并评估了种群大小，气候和猎物丰富度对每种种群的不同影响特定年龄段的人口统计参数。我们在所研究的四个生命率中发现了强有力的年龄效应证据。在所有参数下，较年轻年龄段的生命率均低于较老年人年龄段的生命率。结果清楚地证明了当地气候（夏季海冰浓度），可用猎物资源（企鹅）和内在因素（繁殖种群的大小）的直接和间接影响。发现对生育率的协变量效应大于对生存率的协变量效应，而年龄较小的人群比年龄较大的人群更敏感。确定性年龄结构密度依赖矩阵种群模型的结果表明，猎物丰富度和海冰浓度对总种群规模的影响大于对繁殖种群规模的影响。总人口规模和繁殖者数量都受到海冰浓度偏低的强烈影响。总体而言，我们的研究结果突出表明，繁殖特征和较年轻年龄类别对海洋先头天敌捕食量，气候变异性和密度依赖性的敏感性更高，这对总种群规模具有重要影响，但对繁殖种群规模的影响有限。我们讨论了气候变化的机制，