I am pleased to share our paper (Open Access)
Filatova O.A., Fedutin I.D., Fomin S.V. (2026). Predation by mammal‐eating Bigg's killer whales (Orcinus orca rectipinnus) may shape the unique social structure of “resident” fish‐eating killer whales (O. o. ater) in the North Pacific. Marine Mammal Science, 42(2). https://doi.org/10.1111/mms.70142
The killer whale is a polymorphic species with remarkable behavioral and ecological plasticity, including diverse social structures. North Pacific resident killer whales (Orcinus orca ater) exhibit a unique social system where both male and female offspring remain in their natal groups for life. In contrast, other killer whale ecotypes display more flexible group dynamics, and the benefits of lifelong group membership in residents remain unclear. In other species, group formation is often linked to anti-predator defense, yet killer whales are typically considered apex predators. The only potential predator for a killer whale is another killer whale, but there has been very limited evidence of cannibalism, primarily from historical whaling records. Here, we report the remains of two resident killer whales with distinct killer whale tooth marks, discovered on separate occasions on Bering Island (Commander Islands, Russia). These findings raise the possibility of predation by sympatric Bigg’s killer whales, O. orca rectipinnus. We discuss whether this predation pressure could shape the stable social structure in the resident ecotype.
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