The term '1001 Nights Bird' is a reference to the mythical bird, the ROC, which appears in the classic Middle Eastern collection of stories known as One Thousand and One Nights. The ROC is a giant bird of prey that is said to be able to carry off elephants and other large animals in its talons. The ROC is also sometimes referred to as the Rukh, which is the three-letter answer to this crossword puzzle.