Because whales are marine mammals, the females carry the offspring in their wombs and have live births! They do not lay eggs. However, since whales are fully aquatic mammals, their live births are much different than the births of terrestrial and semi-aquatic animals. This post will walk through the entire whale life cycle and reproductive process from courtship to gestation, birth, and caring for the baby whale calf.
Even though whales live a long time (on average, between 30 to 70 years!), they reach sexual maturity at a relatively young age. Most males can mature between 7-10 years of age, whereas the females’ maturity occurs between 5-7 years of age.
Female whales will have a new calf every two to three years, which is a much longer reproductive cycle than many other marine animals. So, in order to increase their chances of getting pregnant, female whales will often have multiple mating partners during the mating season.
When it comes time for whale mating season, many whales will migrate to warmer waters, especially if they inhabit a colder ocean region. Just like other mammals, whales have their own special behaviors to court female whales during mating season. Males whales will compete for female attention and engage in songs, calls, and even caresses. Female whales can sometimes be choosy when it comes to who they mate with – they have been observed avoiding mating calls for several days even. However, once a female whale is willing to mate, she will mate with several partners over the course of some hours. She does this to increase her chances of getting pregnant, as she will only give birth every 1 to 5 years.
Once a female whale becomes pregnant, her gestation period can vary greatly. Depending on the particular species of whale, a gestation period can be anywhere between 9 to 16 months. Many whale calves will be born during the migration process, as female whales will try to get to warmer waters so their offspring can be born in more temperate conditions.
Because whales are mammals, their calves grow inside their mothers and are born through live births. During birth, calves will emerge fins first. The size of a whale calf will depend on the size of the mother, but generally speaking you can expect it to be about ¼ the length of the mother. So, the whale calf of the blue whale species (the largest whale) will be significantly larger than that of a grey whale, for instance.
Once a female whale gives birth, they typically nudge their calf up to the ocean surface so they can take their first breath.
The mortality rate for calves is extremely high during the first year of its life, so mother whales make sure to keep a very close and protective eye over them especially after they are born. During the first month of life, many whale calves will not sleep meaning mother whales will have to forgo sleep as well to keep a watchful eye on them.
Once a female whale gives birth, her calf will feed off her milk which contains a very high fat percentage and full of nutrients. This high fat concentration also keeps the milk from dissipating in the ocean water. Whale calves will continue to feed off the milk for up to 2 years until it becomes self-sufficient to find its own food. Female whales will nurse underwater, but very close to the surface.
Many animals raise their young until they mature to self-sufficiency, but this is not the case for orca whales, also known as killer whales. One an orca whale calf reaches maturity, it will stay in the pod of whales with the mother for life, even after the offspring has offspring of its own.
Despite the countless whale watching trips around the country and researchers involved in studying whale behavior and activity, the birth of a humpback whale has surprisingly never been seen before. Although an actual humpback birth has never been recorded, there is evidence suggesting that humpback whales give birth during their migration to warmer waters from colder regions, similar to other species. Despite our limited knowledge of humpback whales, it is obvious that the mother and calf have a very close relationship. Whale calves are always close to their mothers and significantly rely on them for food and constant protection.