Shedding enhances the sexual attractiveness of oestradiol treated garter snakes and their untreated penmates

The courtship behaviour of male garter snakes (Thamnophis radix) was tested with females who received or did not receive oestradiol benzoate (EB) injections prior to shedding, and with non-shedding females who received EB. Each female injected for 5 or more days prior to shedding was courted only after the shed. In addition, most penmates of the EB treated shedders were courted frequently after the treated female shed. Females who received no EB prior to shed showed little or no increase in sexual attractiveness. EB treated females who did not shed were inconsistently courted. It is most likely that shedding potentiates the release of a sexual pheromone from the dorsal skin of EB treated females, and this pheromone can then be spread to the backs of penmates.