Caprimulgus is a large and very widespread genus of nightjars. Caprimulgus is derived from the Latin capra, "nanny goat", and mulgere, "to milk", referring to an old myth that nightjars suck milk from goats. The common name "nightjar", first recorded in 1630, refers to the nocturnal habits of the bird, the second part of the name deriving from the distinctive churring song. Caprimulgus species have relatively long bills and rictal bristles. Many have repetitive and often mechanical songs.