Skeleton Bird

Skeleton Birds (スケルトンバード, Sukeruton Bādo), or Flying Ghosts, are enemies in the game Wario Land 4. They appear in the levels of the Sapphire Passage and the level Golden Passage. As their name implies, these creatures are flying skeletal birds that can't be normally destroyed by Wario. Skeleton Birds wear a green hood and a red bandanna and have two flapping wings. They attack by spitting green clumps of goo, which does not actually hurt Wario, but turns him into his zombie form. While Wario is a zombie, he can attack a Skeleton Bird; after hitting it once, it will crumble into a head which Zombie Wario or his normal self can defeat.

In the ending cut-scene, a Skeleton Bird appears with two Men'ono in one of Wario's flashbacks.