Influence of the seminal plug on mating behaviour in the garter snake.

Abstract

PHEROMONES are used by a wide variety of animals to identify the social status, sex and reproductive state of conspecifics1. In snakes, olfactory cues are involved in prey selection and trail following2–4, recent experiments indicate that female sexual attractivity in the garter snake Thamnophis sirtalis is oestrogen-dependent and that sexually active males discriminate between, and preferentially court, oestrogen-injected females5,6. We report here that in the closely related species, T. radix, sexually active males do not court recently mated females. This discrimination is based on the presence of a seminal plug normally deposited by the mating male during copulation, and the mating plug exerts an inhibitory effect on the courtship activity of other males.