Pup's broadband vocalizations and maternal behavior in the rat.

Rat pups emit broadband vocalizations with components extending from the audible to the ultrasonic range. Three experiments were undertaken to determine the circumstances under which the calls are emitted, and the effects that they might have on the maternal female's behavior. In the first study, pups were manipulated by the experimenter in several different ways. Broadband calling occurred when the pup was picked up and moved off the horizontal plane. In a second study, the mother was observed interacting with her litter. Vocalizations occurred most often when the mother engaged in behaviors that brought her into contact with the pups, such as nest entry, moving while in the nest, and pup licking. In another experiment, females were temporarily deafened. Relative to controls, deafened females engaged in more incidental contact with the pups, although only if the female was deafened during the first of two tests, when the pups were two days old. Broadband calling may function to reduce rough handling or inadvertent contact by the mother.