The mating system of Hyperoodon ampullatus is believed to be polygynous, with a single mature male associating with a group of females during the mating season.
Mating System: polygynous
Females become sexually mature at a length of 6.7-7m (8-14 years) and males reach maturity at 7.3-7.6m (7-9 years) (Evans 1987, MacDonald 1987, Minasian et al. 1984).
Mating occurs in spring and early summer and calves are born from April to June. Data from the Gully population near Nova Scotia indicates that the mating and calving period for this population may be from June to August. The gestation period for all Northern bottlenose whales is around twelve months and females exhibit a calving interval of two to three years. (Whitehead et al. 1997a, MacDonald 1987, Reeves et al. 1993, Tinker 1988).
Breeding interval: Females exhibit a calving interval of two to three years
Breeding season: Mating occurs in spring and early summer
Average gestation period: 12 months.
Average weaning age: 12 months.
Range age at sexual or reproductive maturity (female): 8 to 14 years.
Range age at sexual or reproductive maturity (male): 7 to 9 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average gestation period: 365 days.
Average number of offspring: 1.
Calves are around 3.5m in length at birth and weaning occurs at around one year of age.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)