Anonymous

You could ask that question of every migrating species of bird, land animal, fish, etc. Many of them, especially fish and birds, travel much longer distances every year than the distance from parts of Africa to Europe and the British Isles.

Anonymous

Habit, developed over many thousands of years. Like all migrating birds, the main reason is food scarcity, avoiding predators and disease, and spreading out during breeding season.

Anonymous

They are animals with a natural instinct. There's no "why" for what they do.

Anonymous

Because they are cuckoo.