The average amount of time it takes for a female whale to have a baby varies depending on its species.
A whales pregnancy cycle can last anywhere from 10 months all the way up to 18 months and on average a female whale will bare a single offspring once every 1 – 6 years while she is fertile.
In rare cases a female whale may bare twins, but this is very uncommon and rarely seen among the whale population.
During the gestation period the baby whale develops and grows in the mothers uterus and is fed nutrients and blood through an umbilical cord.
Upon birth the baby whale is usually delivered tail first in order to prevent the possibility of drowning, although in some situations a whale may also be delivered head first.
For the first several months after birth the baby whale feeds by suckling milk from their mothers nipple.
Depending on the species and their psychological dependency on their mother some whales may be seen suckling for as long as 24 months, and in some cases the baby may continue to suckle even after the mother is no longer lactating.
While the average age of maturity varies from species to species most whales will mature between the ages of 5 – 15 at which point they can then begin mating and bearing offspring of their own.
In a pod or family the baby whale is known as a calf, the female whale is known as cow and the male is referred to as the bull.
During mating season various species of whale can be seen traveling towards the equator to take advantage of the warmer climates and begin mating and/or baring offspring.
While this period varies from species to species and depending on the climate they live in mating season typically occurs during the colder winter months of the year when the waters begin to freeze over and their food supply begins to migrate away and move towards warmer climates.
Once mating season ends the various species of whale travel back to their feeding grounds and begin stocking up on food until the next mating season comes around.
While mating season and migration cycles are important to many species of whale not all species are known to migrate during the colder months.
Some species such as the bowhead whale are known to live in the same arctic/sub arctic waters throughout the year and may only make small migration trips from time to time.
A list of the average gestation periods of several whale species
- Minke whales have an estimated gestation period of 10 months with females baring a single offspring every 2 years or so.
- Narwhal whales are believed to take an average of 14 – 15 months between pregnancy and birth with an estimated average of 1 offspring every 3 years while fertile.
- Sperm whales are estimated to have a 14 – 16 month gestation period and females whales give birth every 3 – 6 years.
- Gray whales are assumed to have a pregnancy period 13.5 months (data not available on birth frequency)
- Humpback whales have an 11 - 12 month pregnancy range and reproduction occurs every 2 – 3 years after sexual maturity is reached.
- Beluga whales are estimated to have a pregnancy period of 14 – 15 months and female whales give birth every 3 years or so.
- Blue whales give birth after 11 – 12 months of pregnancy and it is estimated that female whales give birth every 2 – 3 years.
- Killer whales have a pregnancy period of 15 – 18 months, however it is believed that the average pregnancy period is about 17 months. (Females killer whales give birth every 3 – 5 years).