Evolutionary trade-offs between fecundity and survival are ubiquitous in evolution. In high-latitude seasonal environments, most birds breed during resource-rich summers, and migrate to lower-latitude environments during the winter to survive. However, the trade-off between fecundity and survival appears to scale with migration distance: By migrating farther, birds may gain higher survival benefits, but in doing so, they sacrifice time that they might have spent raising offspring. Longer migrations are thus associated with "slower" life histories (higher survival, fewer offspring), but this apparently straightforward trade-off belies an intriguing underlying paradox: Slower life histories are typically associated with lower genetic diversity, but in migratory birds, there is evidence that longer migrations are positively correlated with genetic diversity, possibly because they promote demographic stability. Nevertheless, populations of long-distance migrants readily switch strategies, implying that populations will move quickly toward new optima if migration’s survival benefits no longer outweigh its reproductive costs, with unknown population genetic consequences. My dissertation will combine movement ecology and population genetics to assess the ways in which seasonal migration has mediated life history trade-offs and impacted genetic diversity within species, with the goal of understanding how the risks of migration have translated to rewards over evolutionary timescales.