Orca Groups with Radically Different Cultures Are Actually Separate Species
“Resident” and “transient” killer whales, or orcas, have unique hunting habits and genetics, proving they are in fact separate species
Wide view of two Bigg’s Killer Whales in Washington State.
Cavan Images/Alamy Stock Photo
Two populations of killer whales off the Pacific Northwest coast have clear, major differences in culture: one group hunts down and kills large marine mammals in aggressive coordinated attacks, while the other are relatively docile salmon eaters. Scientists have long wondered whether these two are unique populations of one species (Orcinus orca) or represent subspecies or fully separate species. Now genetic data from a study published March 27 in Royal Society Open Science show these killer whale groups are indeed two distinct species. And there could be more.
One of the Pacific Northwest groups is known as the “residents” because its members live near shore and feed on salmon. The other, called the “transients” (or sometimes Bigg’s killer whales) live farther out in the open ocean and eat hefty mammals, including seals, dolphins and juvenile whales. The groups avoid each other and are rarely seen interacting despite being in the same general area; scientists have long attributed this to a deep cultural divide.
The two populations of killer whales, also known as orcas, have vastly different behaviors and lifestyles. Residents, for example, form large family groups, or pods, of closely related individuals that number up to 20 or more. Pods occasionally intermingle, and such gatherings can be magnificent to watch. The late researcher Ken Balcomb wrote about making a foggy trip into Washington State’s Puget Sound with his colleagues for orca research when three resident pods—more than 80 animals in all—gathered around the scientists’ boat and swam beside it for two hours until the fog lifted. “Did they know that we couldn’t…
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