Auditory regulation of woodrat ( Neotoma lepida) sexual behaviour

Abstract

Male desert woodrats, Neotoma lepida, produce an audible rasping vocalization during copulation. In a normative experiment, it was shown that the call was associated with behaviour patterns that generally occur shortly before intromission: hop-darting and lordosis in the female, and trailing and mounting in the male. Two complementary experiments were done to determine whether the male's call affected female sexual behaviour: in one the female was temporarily deafened, and in the other, the male was temporarily devocalized. In both experiments, the female displayed fewer lordosis responses to male mounting when communication of the rasping call was prevented. In a subsequent experiment, taped male vocalizations were played at the time calling would usually occur, to pairs consisting of an intact female and a devocalized male. Playback restored female lordosis behaviour to levels seen in intact controls. The male, however, was unable to obtain intromissions when mounting the female. Finally, micro-analysis of videotapes of copulating pairs confirmed that females exhibited fewer lordosis responses when the male was devocalized. Those that did occur were of poorer quality in terms of head elevation and onset latency. Playback restored these behaviours to control levels. Males gave similar amounts of flank and perineal stimulation to the female in each condition. The results of the study suggest that the male's call facilitates receptive behaviour such as lordosis in the female woodrat.