A purr or whirr is a tonal fluttering sound made by some species of felids, including both larger, wild cats and the domestic cat, as well as two species of genets and the Caquetá titi monkey. It varies in loudness and tone among species and in the same animal. Although true purring is exclusive to felids and viverrids, other animals such as raccoons produce vocalizations that sound similar to true purring. Animals that produce purr-like sounds include mongooses, kangaroos, wallabies, wallaroos, badgers, rabbits, foxes, and guinea pigs.