Asymmetrical turning during spermatophore transfer in the male smooth newt

During mating, male smooth newts, Triturus vulgarisshowed a population bias for turning left during spermatophore transfer. This is the first demonstration of asymmetrical sexual behaviour in an amphibian population. An experiment with a perfect female model showed that it was due to male rather than female lateralization. Left turning bias decreased progressively as more spermatophores were deposited, and no significant bias was detectable by the third deposition. The hypothesis that this was due to neuromuscular fatigue was tested but not supported. Turning orientation had no influence on the probability of the female picking up the spermatophore in her cloaca. The left turning bias has not been found in the great crested newt, T. cristatus