Female voles discriminate males' over-marks and prefer top-scent males

Scent over-marking is a common form of competitive advertisement among many species of mammals. Recent observations in golden hamsters, Mesocricetus auratus, have suggested that individuals have specialized mechanisms for interpretation of and response to such over-marks. In this study, we examined whether meadow voles, Microtus pennsylvanicus, have similar abilities. Female voles were first exposed to anogenital scent marks of two males and were then tested in a Y-maze for their preferences for whole-body odours of these two males. Experiments were run using a variety of configurations of scent marks during the exposure phase, but all experiments yielded consistent results. If the scent marks of the two males overlapped, females later preferred the whole-body odours of the male whose scent was on top; if the two scent marks did not overlap, females showed no preference. Females also preferred odours of familiar males over novel males, and preferred both top-scent and bottom-scent males over novel males. The results suggest that female voles can tell which individual's scent is on top in an over-mark and that they prefer this top-scent male, even though they know that both males' scents were present during the exposure phase. We suggest that these odour preferences reflect mate preferences and discuss possible reasons why females might prefer top-scent males. (C) 1997 The Association for the Study of Animal Behaviour.