Various benefits (e.g. tracking of resources and of climate niche) and costs (e.g. distance travelled) are hypothesized to drive seasonal animal migrations. Until now, these potential factors have been investigated together at the species level, but migratory movements are made at the individual level, leading to intraspecific variability. Here, we use ringing/recovery data from 1308 individuals belonging to thirteen North American bird species to analyse patterns in intraspecific variability of migratory destinations in order to investigate which factors underpin bird migration and how individuals trade‐off among multiple factors. Our results suggest that migratory destinations have been shaped by access to resources (most important during the breeding season) and climatic niche tracking (during winter, mostly). However, the benefits of resource surpluses and climate niche tracking appear to be traded off against the cost of migratory distance, which seems to strongly constrain where individuals migrate.

中文翻译：

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探索迁徙目的地的种内差异，以调查迁移的动因

各种利益（例如，对资源和气候利基的追踪）和成本（例如，行进距离）被假定为推动季节性动物迁徙。到目前为止，已经在物种水平上一起研究了这些潜在因素，但是在个体水平上进行了迁徙运动，从而导致种内变异。在这里，我们使用来自13种北美鸟类的1308个个体的振铃/恢复数据来分析迁徙目的地的种内变异性模式，以调查哪些因素支撑了鸟类的迁徙以及个体如何在多种因素之间进行权衡。我们的结果表明，迁徙目的地是由对资源的访问（在繁殖季节最重要）和对生态位的跟踪（主要在冬季）形成的。然而，