What is the gestation period of a killer whale?

A killer whale’s gestation period is about 17–18 months. Estimates vary by study and population, but pregnancies commonly fall within a broader range of roughly 15–18 months.

Killer whales, or orcas (Orcinus orca), usually give birth to a single calf. Because conception is difficult to observe in wild whales, researchers often estimate gestation from known birth dates, hormone data, or the interval between observations of a female and her calf.

The long pregnancy reflects the demands of producing a highly developed calf. Newborns must swim immediately, surface for air, and remain closely associated with their mothers and pod. Calves nurse for at least a year, while their close relationship with the mother generally continues much longer.

A common mistake is to assume every whale has a similar pregnancy length. Gestation varies substantially among cetaceans: sperm whales generally carry calves for about 14–16 months, while many baleen whales have pregnancies close to a year. Orca births can occur in any month rather than during one fixed season.