Nightjars are medium-sized nocturnal or crepuscular birds in the family Caprimulgidae, characterized by long wings, short legs and very short bills. They are sometimes called goatsuckers, due to the ancient folk tale that they sucked the milk from goats (the Latin for goatsucker is Caprimulgus). Some New World species are called nighthawks. Nightjars usually nest on the ground. The English word 'nightjar' originally referred to the European nightjar.