Joseph McCallum

1 INTRODUCTION Despite being an activity that carries a very high level of risk (Alerstam et al., 2003; Mangel & Satterthwaite, 2008), long-distance migration has evolved on multiple occasions in multiple lineages (Cresswell et al., 2011). Migration should only evolve and be maintained in a species when the fitness benefits of migrating outweigh its costs (Adams et al., 2022; Mangel & Satterthwaite, 2008).