Orcas from the southern resident population off western US and Canada Center for Whale Research/David K. Ellifrit
Off the Pacific coasts of the US and Canada, orca mothers provide food for their sons long after they reach adulthood, even though this restricts them from having more surviving offspring.
Orcas, also known as killer whales (Orcinus orca), give birth after 15 to 18 months of gestation and nurse their young for about two years. However, in the southern resident populations that live off the coasts of Washington state and British Columbia, only about a third of pregnancies …
