Female mimicry in garter snakes

Nature. 1985 Jul 4-10;316(6023):59-60. doi: 10.1038/316059a0.


In many diverse taxa, males of the same species often exhibit multiple mating strategies. One well-documented alternative male reproductive pattern is 'female mimicry', whereby males assume a female-like morphology or mimic female behaviour patterns. In some species males mimic both female morphology and behaviour. We report here female mimicry in a reptile, the red-sided garter snake (Thamnophis sirtalis parietalis). This form of mimicry is unique in that it is expressed as a physiological feminization. Courting male red-sided garter snakes detect a female-specific pheromone and normally avoid courting other males. However, a small proportion of males release a pheromone that attracts other males, as though they were females. In the field, mating aggregations of 5-17 males were observed formed around these individual attractive males, which we have termed 'she-males'. In competitive mating trails, she-males mated with females significantly more often than did normal males, demonstrating not only reproductive competence but also a possible selective advantage to males with this female-like pheromone.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Female
  • Gonadal Steroid Hormones / blood
  • Humans
  • Male
  • Pheromones / biosynthesis
  • Sexual Behavior, Animal*
  • Snakes / physiology*


  • Gonadal Steroid Hormones
  • Pheromones