EFFECTS OF PREGNANCY, LACTATION AND POSTPARTUM ESTRUS ON ODOR SIGNALSAND THE ATTRACTION TO ODORS IN FEMALE MEADOW VOLES, MICROTUS-PENNSYLVANICUS

Our understanding of communication by female mammals about reproductiv e state is currently limited by a paucity of information about signall ing during pregnancy and lactation. To address this situation, odour c ommunication was examined in meadow voles by means of preference tests . In experiment 1, males showed no preference for odours of a referenc e female versus a pregnant female or odours of a reference female vers us a lactating female throughout most of pregnancy and lactation. Howe ver, preferential attraction to one of these scents occurred around pa rturition. Just before parturition (day 19-20 of gestation) males show ed a preference for the odour of a reference female over that of a pre gnant female. Immediately after parturition, during postpartum oestrus (day 1-2 of lactation), however, male preferences reversed so that ma les preferred scent of a postpartum oestrous female over that of a ref erence female. In experiment 2, the odour preferences of females were examined across pregnancy and lactation. Females maintained a preferen ce for odours of a male over a reference female during pregnancy, post partum oestrus and lactation. These results differ from those reported for other species in which females show a repeated oestrous cycle. Th ese results also suggest the existence of some complexities of odour c ommunication during the transition from pregnancy, postpartum oestrus and lactation in a species in which females show an induced oestrus.