Measurements of immune function in migrating birds from Recovery of constitutive immune function after migratory endurance flight in free-living birds

Strenuous physical activity can negatively affect constitutive innate immune function (CIF), the always present first line of defence against pathogens. CIF is non-specific, and thus vital when encountering novel pathogens. A lowered CIF likely increases the risk of infection and disease. Migratory birds engage in truly extreme physical activity during their endurance flights, however, little is known about how they deal with the negative impact this has on their immune function. By collecting both between- and within-individual data we show, for the first time, that free-flying migratory birds can recover several parameters of CIF during stopovers, which are stationary periods in between migratory flights. With this, we provide an important piece of the puzzle on how migrating birds cope with the physiological challenges they face on their biannual journeys. Furthermore, our study stresses the importance of migratory stopovers beyond fuel accumulation.

高强度体力活动可对组成型固有免疫功能（constitutive innate immune function, CIF）产生负面影响——该功能是机体始终存在的抵御病原体的第一道免疫防线。组成型固有免疫功能属于非特异性免疫，因此在遭遇新型病原体时至关重要。CIF水平降低可能会提升感染与患病风险。候鸟在长距离持续飞行期间会开展近乎极限的体力活动，但目前学界对其如何应对该活动对免疫功能造成的负面影响尚缺乏足够认知。本研究通过采集个体间与个体内的双重数据，首次证实自由飞行的候鸟能够在迁飞停歇期——即两次迁飞之间的静止休整阶段——恢复多项组成型固有免疫功能指标。借此，我们为解析候鸟在年度两次迁飞旅程中如何应对其所面临的生理挑战这一谜题补上了关键一环。此外，本研究还强调了迁飞停歇期除蓄积能量之外的重要意义。