A new study has found that the humpback whale will come to the defense of other marine mammals that are under attack from orcas whales. The study examined the motivation for what at first blush appears to be an altruistic behavior.
Robert Pitman is a marine ecologist in southern California’s National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center and was the lead author of the study. Pitman and his team documented cases of Humpbacks coming to the rescue of grey whales, seals and other marine mammals.
The mammals rescued by humpbacks were fleeing from orcas, also known as killer whales, and in danger of becoming a meal. Pitman told CBC radio’s Early Edition that the aggressive humpbacks are not just being good neighbors, however.
Orcas also attack humpback calves and Pitman believes adult humpbacks will attack the orcas even if a humpback calf is not the prey because they are accustomed to doing so. So upon hearing an orca attack, even from as far away as two kilometres, the humpback goes into action and heads to the rescue.
Humpback whale tails
When the humpback arrives on scene, CBC reporter Roshini Nair notes “orcas are actually the ones that could be in danger” as humpbacks have tails up to 18 feet long and swing it with great force. Nair said Pitman told her a humpback’s tail “could easily deliver a lethal blow to an adult killer whale.”
Pitman said he became interested in the subject after seeing a seal that was being chased by an orca get rescued by a humpback. The humpback swam into the path of the seal and lay on its back and angled itself so waves pushed the seal on its belly; when the seal slipped toward the water the humpback used its fin to push it back to the safety of its stomach.
What he saw “shocked” him and Pittman wanted to learn if such things happened regularly. A part of the documentation in the study came from interviewing other marine researchers who had witnessed scenes of humpbacks rescuing marine mammals from killer whales.
The study was published in the journal Marine Mammal Science and titled: Humpback whales interfering when mammal-eating killer whales attack other species: Mobbing behavior and interspecific altruism?