Data from: Brain regions associated with visual cues are important for bird migration

Long-distance migratory birds possess smaller brains relative to their body mass than short-distance migrants or residents. Here, we test whether reduction in brain size with migration distance can be generalized across the different brain regions previously suggested to play key roles in orientation during migratory flight. Based on 152 bird species, belonging to 61 avian families from 6 continents, we show that the sizes of both the telencephalon and the whole brain decreases, while the relative size of the optic lobe increases with increasing migration distance. Additionally, we show that migration distance is not significantly associated with the size of the cerebellum. Controlling for wing morphology did not alter our conclusions. Body mass, whole brain size, optic lobe size and wing aspect ratio together account for a remarkable 46% of interspecific variation in average migration distance across bird species. These results indicate that visual acuity might be a primary neural adaptation to the ecological challenge of migration.

长距离迁徙鸟类的相对脑尺寸（即脑尺寸与体重的比值）小于短距离迁徙鸟类或留鸟。本研究旨在检验：随迁徙距离增加而出现的脑尺寸缩减现象，是否可推广至此前被认为在迁徙飞行定向中发挥关键作用的各类脑区。研究纳入了源自6大洲、隶属于61个鸟类科的152个鸟类物种，结果显示：端脑（telencephalon）与全脑的尺寸均随迁徙距离增加而减小，而视叶（optic lobe）的相对尺寸则随迁徙距离增加而增大。此外，迁徙距离与小脑（cerebellum）的尺寸无显著关联。在控制翼形态变量后，本研究的核心结论并未发生改变。体重、全脑尺寸、视叶尺寸以及翼展比（wing aspect ratio）共同解释了鸟类物种间平均迁徙距离46%的种间变异，这一解释度颇为可观。上述结果表明，视觉敏锐度或许是应对迁徙生态挑战的主要神经适应性特征。