In the Philippines when an ASWANG decides that it no longer wishes to hunt for its human prey itself, it moves to the swampy regions of the country and becomes a hayopan. Physically, nothing has changed and the vampire is still an aswang in every way. The only thing that has changed, other than its new geographic location, is how it hunts. Still desirous of consuming human blood, the hayopan raises and trains a float of crocodiles to hunt and return with food for it.

Source: Gardner, Philippine Folklore, 7; Redfern, Strange Secrets, 153; Rodell, Culture and Customs, 31