A. Sexual maturity.
1. Field studies on many aspects of killer whale reproduction are
not available, yet much has been learned at marine life parks. Studies of killer
whales in marine zoological facilities suggest that females become sexually mature when
they reach 4.6 to 4.9 m (15-16 ft.), at about 6 to 10 years.
2. Males usually become sexually mature when they reach about 5.5 to 6.1 m (18-20
ft.), at about 10 to 13 years. In the SeaWorld Adventure Park system, one male
successfully mated at approximately 7.5 to 8 years of age. In the wild, social
factors greatly influence a male's breeding success. Males may not successfully
reproduce until they are much older, larger, and more able to compete with other males.
B. Mating activity.
1. Killer whales are considered polygamous as they tend to mate
with any number of partners.
2. 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 estrus cycling (polyestrus), interspersed with periods of non-cycling.
This period is highly variable, as is the period of non-cycling, both for one whale over
time, and between whales.
3. Breeding may occur in any season, but it is most common
in the summer. In the North Atlantic, mating seems to peak in October and November;
in the western North Pacific, mating seems to be at its highest between May and June.
