SEXUAL-BEHAVIOR OF MALE AND FEMALE TAMMAR WALLABIES (MACROPUS-EUGENII) AT POSTPARTUM ESTRUS

This study describes the sexual behaviour of the adult male and female tammar wallaby from the time a female gives birth to the end of post-partum oestrus. Eleven females were continuously observed from around the time of birth until up to 3 h after the last observed mating attempt. Males began to associate with females from around the time of birth, thus females appear to be attractive to males at, but not prior to parturition. Females subsequently allowed males to mate with them from 1.3 +/- 0.8 h (mean +/- S.D.) post-partum, although the first ejaculation was delayed until 1.8 +/- 0.8 h after birth owing to intense intermale aggression directed towards any male which attempted to mate with an oestrous female. Mating chases, in which a post-partum female was pursued by several males, were observed from 1.3 +/- 0.8 h post-partum. All of this mating activity usually occurred within the first 6 h after birth. The most dominant (alpha) male always ejaculated first and subsequently guarded the female for up to 8 h, thereby preventing most subordinate males from mating during that period. After that time, most alpha males ceased their guarding activities, thereby allowing subordinate males to mate. Thus, the tammar is a polygynous, multi-male mating species in which the alpha male appears to have mating advantages over subordinate males. The large relative testis size and the extent of the sexual dimorphism in body size is a reflection of this mating system.