Data from: Pulsed food resources, but not forest cover, determines lifetime reproductive success in a forest-dwelling rodent

1. The relative contributions of habitat and food availability on fitness may provide evidence for key habitat features needed to safeguard population persistence. However, defining habitat quality for a species can be a complex task, especially if knowledge on the relationship between individual performance and habitat quality is lacking. 2. Here, we determined the relative importance of availability of suitable forest habitat, body mass, and food from masting tree species on female lifetime reproductive success (LRS) of Siberian flying squirrels (Pteromys volans). 3. We calculated LRS of 500 female flying squirrels based on a 22 year-long longitudinal data set of two populations from western Finland. We assessed with generalised additive models the potential effects of availability of suitable habitat and cumulative lifetime availability of food from masting tree species on female LRS, longevity and fecundity. On a reduced dataset, we evaluated the importance of female winter body mass and conducted a piecewise path analysis to determine how variables were connected. 4. According to generalised additive models female longevity, fecundity and LRS were mainly determined by variation in cumulative lifetime availability of food from masting alder and birch. Instead, habitat and body mass had smaller role. The path analysis indicated that lifetime food availability had direct effect on longevity and fecundity, and these had equal effect on LRS at both study sites. 5. Our results on LRS shows that the occurrence of tree masting events during a flying squirrel female’s lifetime have profoundly larger effect on lifetime reproductive success than the cover of suitable forest habitat. Furthermore, this study emphasises the importance of both fecundity and longevity, and the indirect effects of food availability via those components, as determinants of lifetime fitness of female flying squirrels.

1. 生境与食物可获得性对个体适合度的相对贡献，可为保障种群存续所需的关键生境特征提供科学依据。然而，界定某一物种的生境质量往往是一项复杂工作，尤其是在缺乏个体表现与生境质量之间关联认知的情况下。2. 本研究旨在明确适宜森林生境可获得性、体重以及大年结实树种食物可获得性对西伯利亚飞鼠（*Pteromys volans*）雌性个体终生繁殖成功率（Lifetime Reproductive Success, LRS）的相对重要性。3. 本研究基于芬兰西部两个种群长达22年的纵向数据集，计算了500只雌性飞鼠的终生繁殖成功率。我们采用广义加性模型（Generalized Additive Models, GAM），分析了适宜生境可获得性、大年结实树种食物的终生累积可获得性对雌性飞鼠终生繁殖成功率、寿命及繁殖力的潜在影响。此外，我们通过缩减后的数据集评估了雌性冬季体重的重要性，并开展分段路径分析以明确各变量间的关联机制。4. 广义加性模型结果显示，雌性飞鼠的寿命、繁殖力及终生繁殖成功率主要受大年结实桤木与桦木的终生食物可获得性变化的调控，而生境与体重的作用相对较小。路径分析结果表明，在两个研究样地中，终生食物可获得性对寿命与繁殖力均存在直接正向影响，且二者对终生繁殖成功率的作用强度在两个研究样地中均保持一致。5. 本研究关于终生繁殖成功率的结果表明，雌性飞鼠一生中遭遇的树木结实大年事件，对其终生繁殖成功率的影响远高于适宜森林生境的覆盖度。此外，本研究强调，繁殖力与寿命均是雌性飞鼠个体终生适合度的关键决定因素，而食物可获得性可通过这两个组分产生间接影响。