Vocal mother–pup communication in guinea pigs: effects of call familiarity and female reproductive state

Vocal communication is of special importance in mother–offspring interactions in many precocial mammals, where the offspring are highly mobile. Newborn guinea pigs, Cavia aperea f. porcellus, make distinct calls when separated from their mother. Assuming that offspring separation calls are important in mother–offspring communication, we predicted guinea pig females would respond more strongly to calls of their own than to calls from unfamiliar pups or other guinea pig calls and would respond to pup calls only during lactation when responses are adaptive. In playback experiments, we tested lactating females' responses to separation calls from their own pups and from unfamiliar pups and to female contact calls. We also tested responses by females in late pregnancy (days 50–60) to separation pup calls. Lactating females responded with significantly more vocalizations to their own and to unfamiliar pup calls than to control sounds. Mothers also responded significantly more strongly to playback of calls from their own pups than to calls from unfamiliar pups, suggesting that mothers are able to use vocal cues in pup recognition. The reproductive state significantly influenced responses: lactating females always responded to pup calls, whereas pregnant females did not respond, suggesting that responsiveness is state dependent.