The libidinous newt. An analysis of variations in the sexual behaviour of the male smooth newt, Triturus vulgaris

Abstract

In an experiment designed to investigate variations in the behaviour of male newts in response to female behaviour, five males were tested for each of forty consecutive days in a standard 5-min trial in which the female's behaviour was controlled by the experimenter. In all males there was a steady decline over the 40 days in the number of spermatophores produced, i.e. the number of sexual sequences completed during the 5-min trial period. A number of scores relating to the frequency of performance of male acts and to their temporal patterning are shown to be correlated with one another and with spermatophore score. The temporal patterning of the male's behaviour in a given sequence is related both to the total number of sequences completed in a trial and to the position of the sequence in question within the trial. Principal components analysis enables a number of correlated scores for a sequence to be expressed as the ‘libido’ score for that sequence. A number of factors which may influence the temporal patterning of the male's behaviour are discussed, and it is suggested that the amount of sperm available and the need to ascend to the surface to breathe may be the most important.