Do migratory birds need stopovers for physiological recovery?

大多数候鸟，特别是夜间候鸟，不能一次飞行就达到最终的迁徙目标，因此不得不中途停留以积累新的燃料。中途停留也通常被认为是移民从迁徙耐力飞行中恢复或休息的时期；然而，这种休息和恢复包括什么并不为人所知。作为夜间耐力飞行的结果，候鸟积累了睡眠债务，并经历了破坏性促氧化剂和保护性抗氧化剂之间的平衡向前者转移。因此，这些生理功能似乎需要在中途停留期间恢复。我建议通过测试(I)候鸟在中途停留时是否能促进他们的生理状态(氧化平衡和/或睡眠)，以及(Ii)决定离开中途停留以恢复候鸟迁徙的决定，来显著加深我们对候鸟中途停留的功能的理解。在这里，我将收集关于草酸浓度(睡眠欠债的生物标记物)和移民在中途停留时的氧化平衡的纵向数据，并将这些与离开决定联系起来。

Most migrating birds, especially nocturnal migrants, cannot reach their final migratory goal in a single flight and thus have to make stopovers to accumulate new fuel. Stopovers are also commonly thought of as periods during which migrants 'rest' or recover from migratory endurance flight; however, what such rest and recovery encompasses is not well known. As a consequence of nocturnal endurance flight, migrants build up a sleep debt and experience a shift in the balance between damaging pro-oxidants and protective antioxidants towards the former. Therefore it seems plausible that these physiological functions need to be recovered during stopover. I propose to significantly further our understanding of the functions that stopovers have for migrating birds by testing whether (i) migrants can boost their physiological state (oxidative balance and/or sleep) while at stopover, and (ii) the decision to depart from stopover to resume migration is affected by the bird’s physiological state. Hereto, I will collect longitudinal data on oxalic acid concentrations (a bio-marker of sleep debt) and the oxidative balance of migrants at stopover as well as link these to departure decisions.