There is no information available regarding the mating system of Heaviside's dolphins. However, bottlenose dolphins, spinner dolphins, and common dolphins are promiscuous.
Heaviside's dolphins breed once every 2 to 4 years from spring to late summer. Gestation lasts for 10 to 11 months. Females usually give birth to only one offspring at a time, as there is limited space for in utero development. To account for the limited space in the uterus, during development, the tail flukes and dorsal fins of fetuses are cartilaginous and fold over. Newborns average 85 cm in length. Birth mass has not been recorded for this species. However, newborn bottlenose dolphins range from 11.3 to 18.1 kg, and Irrawaddy dolphins, which average 96 cm in length at birth, has an average birth mass of 12.3 kg. There is no information available regarding weaning and time to independence for this species. Bottlenose dolphins begin weaning as early as 32 months and are fully weaned by 48 months, while time to independence ranges between 3 and 6 years. Female Heaviside's dolphins reach sexual maturity between 5 and 9 years of age, and males reach sexual maturity between 6 and 9 years of age.
Breeding interval: Haviside's dolphins breed every 2 to 4 years.
Breeding season: Haviside's dolphins breed from spring to late summer.
Range gestation period: 10 to 11 months.
Range age at sexual or reproductive maturity (female): 5 to 9 years.
Range age at sexual or reproductive maturity (male): 6 to 9 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Cephalorhynchus heavisidii calves swim in echelon position, that is, in close proximity to the mid-lateral flank near the dorsal fin of the mother. This allows the calf extra speed at a lower tailbeat frequency, because it is able to ride along the pressure wave that its mother’s body creates. However, it has been shown that this causes extra strain on the mother, who is able to swim at only 76% of her mean maximum speed when swimming by her self. Most dolphin calves develop strong social bonds with their mother, which remains even at 3 years of age. This extended mother-young association is thought to be due largely to the still-improving physical performance and social skills of calves. There is no information available regarding paternal investment in calf development.
Parental Investment: precocial ; female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); extended period of juvenile learning