Thursday March 28, 2024

Scientific American

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.

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