The reproductive behavior and breeding cycle of orcas in the wild is not precisely known. Current research, primarily based on study in oceanariums, indicates that there is not a specific breeding season for this species.
Females enter estrus, or heat, several times a year.
Timing seems to vary regionally, and mating and calving seem to occur over several months, although it appears to be most common during the summer months. Research in aquariums indicates that females become sexually mature at around 9 to 10 years of age, and it is believed that wild females give birth to their first calf between the ages of 11 and 17. Males between the ages of 12 and 13 show a noticeable growth in their dorsal fins but do not reach full size until their late teens or early twenties. Females may give birth as frequently as every three years, but may wait as long as eight years. This coloration changes to white at about one year of age.