To use ornithologists 'phraseology, most cuckoo species are migratory, and fly south to avoid the cold of winter. When the weather turns warm again, the cuckoos move back northwards, following the sun and the availability of food.
套用鳥類學者的說法，許多杜鵑是遷移性鳥類，在南方避過寒冬，待天候乍暖還寒，杜鵑追隨陽光、追隨食物，往北遷移。