Abstract Understanding the drivers of movement, migration and distribution of individuals is important for insight into how species will respond to changing environmental conditions. Both abiotic and biotic factors are thought to influence migratory behavior, but their relative roles are difficult to disentangle. For migratory marine predators, both temperature and prey availability have been shown to be significant predictors of space use, though often researchers rely on physical proxies due to the lack of data on dynamic prey fields. We generated spatially explicit individual-based movement models to evaluate the relative roles of abiotic (sea surface temperature; SST) and biotic (prey availability) factors in driving blue whale (Balaenoptera musculus) movement decisions and migratory behavior in the eastern North Pacific. Using output from a lower trophic ecosystem model coupled with a regional ocean circulation model, we parameterized a blue whale movement model that explicitly incorporates prey fields in addition to physical proxies. A model using both SST and prey data reproduced blue whale foraging behavior including realistic timing of latitudinal migrations. SST- and prey-only population models demonstrated important independent effects of each variable. In particular, the SST-only model revealed that warm temperatures limited krill foraging opportunities but failed to drive seasonal foraging patterns, whereas the prey-only model revealed more realistic seasonal and interannual differences in foraging behavior. Our individual-based movement model helps elucidate the mechanisms underlying migration and demonstrates how fine-scale individual decision-making can lead to emergent migratory behavior at the population level. Moreover, determining the relative effects of the physical environment and prey availability on the movement decisions of threatened species is critical to understand how they may respond to changing ocean conditions.

中文翻译：

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使用基于个体的模型解开紧急迁徙行为的生物和非生物驱动因素

摘要 了解个体移动、迁徙和分布的驱动因素对于深入了解物种将如何应对不断变化的环境条件非常重要。非生物和生物因素都被认为会影响迁徙行为，但它们的相对作用很难理清。对于迁徙的海洋捕食者，温度和猎物的可用性已被证明是空间使用的重要预测因素，尽管由于缺乏动态猎物场的数据，研究人员通常依赖物理代理。我们生成了空间明确的基于个体的运动模型，以评估非生物（海面温度；SST）和生物（猎物可用性）因素在推动北太平洋东部蓝鲸（Balaenoptera musculus）运动决策和迁徙行为中的相对作用。使用低营养生态系统模型的输出与区域海洋环流模型相结合，我们参数化了蓝鲸运动模型，该模型除了物理代理外还明确包含猎物场。一个同时使用 SST 和猎物数据的模型再现了蓝鲸觅食行为，包括真实的纬度迁徙时间。SST 和仅猎物种群模型证明了每个变量的重要独立影响。特别是，仅 SST 模型显示温暖的温度限制了磷虾的觅食机会，但未能驱动季节性觅食模式，而仅猎物模型揭示了更现实的觅食行为的季节性和年际差异。我们基于个体的运动模型有助于阐明迁移的潜在机制，并展示精细的个体决策如何导致人口层面的紧急迁移行为。此外，确定物理环境和猎物可用性对受威胁物种运动决定的相对影响对于了解它们如何应对不断变化的海洋条件至关重要。