Killer Whale - Life Cycle

Life Cycle

Female killer whales mature at around age 15. They then have periods of polyestrous cycling with noncycling periods of between three and 16 months. Gestation varies from 15 to 18 months. Mothers calve, with usually a single offspring, about once every five years. In resident pods, births occur at any time of year, although winter is the most common. Mortality is extremely high during the first six to seven months of life, when 37–50% of all calves die. Weaning begins at about 12 months and completes by the age of two. According to observations in several regions, all male and female killer whale pod members participate in the care of the young. Killer and pilot whales are the only nonhuman species in which the females are known to go through menopause and live for decades after they have finished breeding. Killer whales are unique among cetaceans, as their heads become shorter as they age.

Females breed until age 40, meaning on average they raise five offspring. The lifespans of wild females average 50 years, with a maximum of 80–90 years. Males sexually mature at the age of 15, but do not typically reproduce until age 21. Wild males live around 29 years on average, with a maximum of 50–60 years. One male, known as Old Tom, was reportedly spotted every winter between the 1840s and 1930 off New South Wales, Australia. This would have made him up to 90 years old. Examination of his teeth indicated he died around age 35, but this method of age determination is now believed to be inaccurate for older animals. One male known to researchers in the Pacific Northwest (identified as J1) was estimated to have been 59 years old when he died in 2010. Captive killer whale lifespans are typically significantly shorter, usually less than 25 years; however, numerous individuals are alive in their 30s, and a few have reached their 40s. In many instances, the lifespans of killer whales depend on the will of the animal.