Intraspecific variation in home range size has important implications for the distribution of animals across landscapes and the spatial structuring of population, community, and ecosystem processes. Among species of similar trophic guild and body mass, differences in home range size can reflect extrinsic variables that exert divergent selective forces upon spacing behavior and social organization. We tested predictions about how resource availability and timing influence social system, home range size, and territoriality in two tree squirrel species of similar size and ecological niches but that differ in foraging strategy and social organization. We estimated home range size and intraspecific home range core overlap in the Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis; Arizona USA; MGRS) and the Eurasian red squirrel (Sciurus vulgaris; Alps, Italy; ERS) as functions of species, sex, season, and individual’s body mass. However, body mass did not explain differences found between the two species. We found MGRS home ranges being three times smaller with higher core area exclusivity compared to ERS in all seasons. In fact, territorial MGRS evolved in a system of brief resource pulses and are larder hoarders, whereas ERS experience prolonged resource availability and are non-territorial. Only male MGRSs increased their home range during the breeding season, reflecting interspecific differences in social organization and mating behavior. Male ERS home ranges always overlap with several females to enhance mating success although male and female MGRS maintain nearly exclusive territories throughout the year. Only during spring and summer do males temporarily leave their food-based territory to increase mating opportunities with neighboring estrus females. Home range comparisons between ecologically similar species emphasize the importance of divergent extrinsic factors in shaping variability in body size–home range size scaling relationships. Timing in resource availability influenced the social structure and space use in tree squirrels of similar body size, highlighting how the coevolution of arboreal squirrels with conifer tree species has shaped their natural history.

中文翻译：

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资源可用性的时间驱动生态相似树松鼠的不同社会系统和家庭范围动态

家庭范围大小的种内变化对动物在景观中的分布以及人口、社区和生态系统过程的空间结构具有重要意义。在具有相似营养行会和体重的物种中，家庭范围大小的差异可以反映外在变量，这些变量对间隔行为和社会组织施加不同的选择力。我们测试了关于资源可用性和时间如何影响两种大小和生态位相似但觅食策略和社会组织不同的松鼠物种的社会系统、家庭范围大小和领土的预测。我们估计了 Mt. 的家庭范围大小和种内家庭范围核心重叠。格雷厄姆红松鼠（Tamiasciurus fremonti grahamensis；美国亚利桑那州；MGRS）和欧亚红松鼠（Sciurus vulgaris；阿尔卑斯，意大利；ERS）作为物种、性别、季节和个体体重的函数。然而，体重并不能解释这两个物种之间的差异。我们发现，与 ERS ​​相比，MGRS 的住宅范围在所有季节都比 ERS ​​小三倍，并且具有更高的核心区独占性。事实上，领土 MGRS 是在一个短暂的资源脉冲系统中进化的，并且是储藏室囤积者，而 ERS ​​经历了长期的资源可用性并且是非领土的。只有雄性 MGRS 在繁殖季节增加了它们的栖息地，反映了社会组织和交配行为的种间差异。尽管雄性和雌性 MGRS 全年都保持着几乎专属的领地，但雄性 ERS ​​的家庭范围总是与几只雌性重叠，以提高交配成功率。只有在春季和夏季，雄性才会暂时离开以食物为基础的领地，以增加与邻近发情雌性的交配机会。生态相似物种之间的栖息地比较强调了不同的外在因素在塑造体型 - 栖息地大小比例关系的可变性方面的重要性。资源可用性的时间影响了体型相似的松鼠的社会结构和空间利用，突出了树栖松鼠与针叶树树种的共同进化如何塑造了它们的自然历史。生态相似物种之间的栖息地比较强调了不同的外在因素在塑造体型 - 栖息地大小比例关系的可变性方面的重要性。资源可用性的时间影响了体型相似的松鼠的社会结构和空间利用，突出了树栖松鼠与针叶树树种的共同进化如何塑造了它们的自然历史。生态相似物种之间的栖息地比较强调了不同的外在因素在塑造体型 - 栖息地大小比例关系的可变性方面的重要性。资源可用性的时间影响了体型相似的松鼠的社会结构和空间利用，突出了树栖松鼠与针叶树树种的共同进化如何塑造了它们的自然历史。