- Many aspects of killer whale reproduction are not known because they are difficult to study in the wild. Much of what we know about killer whale reproduction comes from studies of killer whales in marine zoological parks.
Marine life parks have been able to learn
a great deal about killer whale reproduction.
- Females become sexually mature when they reach about 4.6 to 4.9 m (15–16 ft.), at about 6 to 10 years.
- Males become sexually mature when they reach about 5.5 to 6.1 m
(18–20 ft.), at about 10 to 13 years.
- In males, dorsal fin growth is probably a secondary sex characteristic. Peak growth of the fin coincides with the onset of sexual maturity.
- At SeaWorld one male successfully mated at about 8 years of age, but in the wild, social factors greatly influence a male’s breeding success. Male killer whales in the wild may not successfully reproduce until they are much older, larger, and able to compete with other males.
- Females come into estrus or “heat” several times during the year.
- Observations of females in zoological parks indicate that killer whales undergo periods of multiple estrous cycling (polyestrus), interspersed with periods of noncycling. On average, females may have four estrous cycles during one polyestrus period. This period is highly variable, as is the period of noncycling, both for one whale over time, and between whales.
- There is no menstrual blood loss.
- Killer whales are polygamous: they mate with several partners.