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适合度的相对贡献，可为维持种群存续所需的关键生境特征提供理论依据。然而，界定某一物种的生境质量往往是一项复杂工作，尤其当缺乏个体表现与生境质量之间关联的相关认知时。
2. 本研究针对西伯利亚飞鼠（Siberian flying squirrels, *Pteromys volans*），明确了适宜森林生境可获得性、体质量以及结实大年树种食物可获得性对雌性个体终身繁殖成功率（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，对500只雌性飞鼠的终身繁殖成功率进行了测算。我们借助广义加性模型（generalised additive models），分析了适宜生境可获得性、结实大年树种食物的终身累积可获得性对雌性飞鼠终身繁殖成功率、寿命以及繁殖力的潜在影响。在精简后的数据集上，我们评估了雌性冬季体质量的重要性，并通过分段路径分析（piecewise path analysis）明确了各变量间的关联路径。
4. 广义加性模型分析结果显示，雌性飞鼠的寿命、繁殖力以及终身繁殖成功率，主要受结实大年桤木与桦树食物的终身累积可获得性变化影响；而生境与体质量的作用相对较小。路径分析表明，在两个研究区域中，终身食物可获得性对寿命与繁殖力均存在直接正向影响，且二者对终身繁殖成功率的贡献程度相当。
5. 本研究关于终身繁殖成功率的结果表明，雌性飞鼠存活期内结实大年事件的发生，对其终身繁殖成功率的影响远大于适宜森林生境的覆盖度。此外，本研究强调，繁殖力与寿命均为雌性飞鼠终身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。