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The Mating Habits of Blue Whales

Blue whales are the largest living animals, reaching lengths of approximately 104 feet. Females are usually longer than males. The highest concentration of blue whales can be found in waters surrounding the Arctic and Antarctic regions, but they also inhabit the Atlantic Ocean, the Pacific Ocean and the Indian Ocean. Despite their extensive range, blue whales are endangered due to excessive hunting in the 20th century. According to the National Geographic Society, between 10,000 and 25,000 blue whales are still believed to exist in 2011. A low reproductive rate contributes to blue whale populations making a slow recovery.

Breeding Season
- The blue whale breeding season usually begins toward the end of the fall and continues throughout winter. Blue whales begin to participate in the breeding season when they reach sexual maturity at between 5 and 10 years of age.
Breeding Behavior
- As the mating season begins, blue whales that normally live and feed in cool or temperate waters begin to migrate to warmer breeding grounds in tropical regions. Blue whales are able to locate each other by producing sounds that can travel thousands of miles underwater. Very little is known about exactly how blue whales mate with each other. Blue whales do not migrate back toward the poles until the mating season has ended. Once a female whale has conceived, she will remain in warmer waters until she has given birth.
Gestation and Birth
- Blue whales usually give birth to one calf after a gestation period that lasts between 10 and 12 months. As mammals, whale calves develop in a womb and receive nourishment from an umbilical cord before the mother gives birth to live young. A newborn whale calf can weigh as much as 3 tons and can measure up to 25 feet in length. Female blue whales have a relatively slow reproductive rate, generally producing just one calf over a period of between two and three years.
Young
- Female whales feed their calves with milk until they are weaned by the age of around 8 months. The thick consistency of blue whale milk is an adaptation that allows mothers to feed their young effectively without the milk disappearing quickly into surrounding waters. While calves are feeding from their mother's milk, they are able to gain weight at a rate of around 200 pounds per day. Blue whales' calves have a faster growth rate than any other animal. Blue whales remain with their mothers until they have been fully weaned and have reached a length of approximately 49 feet.

Animals & Science