Reproduction

Sexual Behaviour and Mating 

Knowledge of the reproductive behaviour of cetaceans in their natural environment is limited. It is known, however, that whales are intensely sexual animals, using sex not only for reproduction, but also for the establishment and maintenance of bonds among all individuals. 

Reproduction Cycle 

The reproduction cycle of most baleen whales is closely geared to their seasonal migration schedule. Mating and breeding takes place during the winter months, after they have reached their breeding grounds. The toothed whales show a variety of life styles, with their breeding season being more extended and not as strictly tied to seasonal changes or migration patterns.  

Giving Birth 

The calves are born tail-first, which is a further adaptation to the life in water. It allows them to remain attached to the placenta, which provides oxygenated blood from the mother, for as long as possible to prevent oxygen deprivation and suffocation.

Birth Rate

The birth rate of Cetaceans is rather low. The gestation period for most species is 11 - 16 months, generally producing only one calf every 2 - 5 years. Multiple births are rare. The mortality (death) rate of the newborn in the first year of its life is often higher than 50%. The low birth rate, coupled with extensive hunting and other environmental threats, explains the rather drastic depletion of several species.