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

Our understanding of communication by female mammals about reproductive state is currently limited by a paucity of information about signalling during pregnancy and lactation. To address this situation, odour communication was examined in meadow voles by means of preference tests. In experiment 1, males showed no preference for odours of a reference female versus a pregnant female or odours of a reference female versus a lactating female throughout most of pregnancy and lactation. However, preferential attraction to one of these scents occurred around parturition. Just before parturition (day 19-20 of gestation) males showed a preference for the odour of a reference female over that of a pregnant female. Immediately after parturition, during postpartum oestrus (day 1-2 of lactation), however, male preferences reversed so that males preferred scent of a postpartum oestrous female over that of a reference female. In experiment 2, the odour preferences of females were examined across pregnancy and lactation. Females maintained a preference for odours of a male over a reference female during pregnancy, postpartum oestrus and lactation. These results differ from those reported for other species in which females show a repeated oestrous cycle. These results also suggest the existence of some complexities of odour communication during the transition from pregnancy, postpartum oestrus and lactation in a species in which females show an induced oestrus.