Sent_en: 2zh The southbound migration was already the smallest in recorded history, and with the destructive winter, over half of the species' population might have been killed.
Sent_yy: 向南迁徙的物种数量已经是有记录以来最小的一次，而且经历了毁灭性的冬天后，超过一半的物种可能已经被杀死了。