As top or mesopredators, carnivores play a key role in food webs. Their survival and reproduction are usually thought to be influenced by prey availability. However, simultaneous monitoring of prey and predators is difficult, making it challenging to evaluate the impacts of prey on carnivores’ demography. Using 13 years of field data on arctic foxes Vulpes lagopus in the Canadian High Arctic and a capture–recapture multi-event statistical approach, we investigated the hypothesis that increases in lemming abundance (a cyclic and unpredictable food source) and goose colony proximity (a stable but spatially and temporally limited food source) would be associated with increased apparent survival and reproduction probabilities of adults. Adult apparent survival varied greatly across years (0.13–1.00) but was neither affected by lemming nor goose variations in abundance. However, reproduction probabilities were strongly influenced by both lemming abundance and access to the goose colony. A fox breeding in the best conditions of food availability (year of high lemming density inside the goose colony) had a reproduction probability four times higher than one experiencing the worst conditions (year of low lemming density outside the goose colony). Breeding status of individuals also played a role, with breeders having a 10–20% higher probability of survival and 30% higher probability of reproduction the following year than non-breeders. As the Arctic ecosystem changes due to increased temperatures and species ranges, this study will allow better predictions of predator responses to management or environmental changes and a better understanding of ecosystem functioning.

作为食肉动物或中食动物，食肉动物在食物网中扮演着关键角色。通常认为它们的生存和繁殖受到猎物可用性的影响。然而，同时监视猎物和掠食者是困难的，这使得评估猎物对食肉动物的人口统计学的影响具有挑战性。利用北极狐Vulpes lagopus的13年实地数据在加拿大高北极地区和采用捕获-捕获多事件统计方法进行的研究中，我们调查了以下假设：旅鼠数量（周期性且不可预测的食物来源）和鹅群体接近度（稳定但在空间和时间上有限的食物来源）增加与成年人明显的生存和繁殖概率增加有关。成年的表观存活率在多年间差异很大（0.13–1.00），但既不受旅鼠的影响，也不受鹅的丰度变化的影响。然而，繁殖的可能性受到旅鼠数量和进入鹅群的强烈影响。在食物可获得性最佳条件下（鹅群内部高旅鼠密度）的狐狸繁殖概率比在最恶劣条件下（鹅群外部低旅鼠密度的年份）繁殖的概率高四倍。个人的育种状况也发挥了作用，与非育种者相比，第二年育种者的存活可能性高出10-20％，繁殖概率高出30％。随着北极生态系统由于温度和物种范围的增加而发生变化，这项研究将使捕食者能够更好地预测其对管理或环境变化的反应，并更好地了解生态系统的功能。与非繁殖者相比，第二年繁殖者的存活概率高10-20％，繁殖概率高30％。随着北极生态系统由于温度和物种范围的增加而发生变化，这项研究将使捕食者能够更好地预测其对管理或环境变化的反应，并更好地了解生态系统的功能。与非繁殖者相比，第二年繁殖者的存活概率高10-20％，繁殖概率高30％。由于北极生态系统由于温度和物种范围的增加而发生变化，因此这项研究将使捕食者能够更好地预测其对管理或环境变化的反应，并能更好地了解生态系统的功能。