The response of meadow voles to an over-mark in which the two donors differ in gonadal hormone status

Abstract

Scent over-marking occurs when an animal places its scent mark directly on top of another individual's scent mark. However, situations may arise in which the top- and bottom-scent donors of an over-mark differ in an individual characteristic(s), for example, gonadal hormone titres. We tested the hypothesis that adult meadow voles, Microtus pennsylvanicus, preferentially respond to a gonadectomized donor treated with gonadal steroid hormones over a gonadectomized donor not treated with gonadal steroid hormones, independently of the position of the scent marks in an over-mark. Male meadow voles spent more time investigating the scent marks of gonadectomized females treated with oestradiol than that of gonadectomized females treated with no oestradiol, independently of the position of the two scent marks in the over-mark. Female voles spent more time investigating the scent marks of gonadectomized males treated with testosterone than that of gonadectomized males treated with no testosterone, only when the former males were the top-scent donors. These results suggest that male meadow voles appear to base their preference on the oestradiol titre of females, rather than the position of the female's mark in an over-mark. In contrast, female meadow voles appear to use both the position of the male's scent mark in an over-mark and the male's testosterone titre for the basis of their preference.