Each year, billions of flying and swimming migrants negotiate the challenging displacement imposed by travelling through a flowing medium. However, little is known about how the ability to cope with drift improves through life and what mechanisms drive its development. We examined 3,140 days of migration by 90 GPS-tagged raptorial black kites (Milvus migrans) aged 1–27 years to show that the ability to compensate for lateral drift develops gradually through many more years than previously appreciated. Drift negotiation was under strong selective pressure, with inferior navigators subject to increased mortality. This progressively selected for adults able to compensate for current cross flows and for previously accumulated drift in a flexible, context-dependent and risk-dependent manner. Displacements accumulated en route carried over to shape the wintering distribution of the population. For many migrants, migratory journeys by younger individuals represent concentrated episodes of trait selection that shape adult populations and mediate their adaptation to climate change.

每年，数十亿飞行和游泳的移民都在通过流动的介质来应对具有挑战性的迁移。然而，人们对如何应对漂移的能力如何在生命中提高以及哪些机制推动其发展知之甚少。我们检查了 90 只带有 GPS 标记的猛禽黑鸢（Milvus migrans) 年龄在 1-27 岁之间，以表明补偿横向漂移的能力逐渐发展，比以前认识到的要长得多。漂移谈判承受着强大的选择压力，劣质导航员的死亡率增加。这逐渐选择了能够以灵活、上下文相关和风险相关的方式补偿当前交叉流动和先前累积的漂移的成年人。途中累积的位移影响了人口的越冬分布。对于许多移民来说，年轻人的迁徙之旅代表了特征选择的集中事件，这些特征选择塑造了成年人群并调节了他们对气候变化的适应。