Cannibalism may explain why some orcas stay in family groups
New Scientist
February 24, 2026
AI-Generated Deep Dive Summary
Cannibalism among orcas may shed light on why certain groups form large family units while others remain more nomadic. In the North Pacific, two distinct subspecies of orcas—Transient (Bigg’s) and Resident—exhibit vastly different social behaviors. Transient orcas are known for their fluid hunting pods, preying on seals, dolphins, and other whales, often moving across vast areas. On the other hand, Resident orcas live in stable, maternally tied groups, staying together throughout their lives. This unique social structure has long puzzled biologists.
Recent discoveries suggest that cannibalism by Transient orcas might explain why Residents form such tight-knit groups. Researchers identified gnawed-off fins from Southern Resident orcas on Bering Island, likely the result of predation by Bigg’s orcas. Genetic testing confirmed the remains belonged to Residents, leading scientists to hypothesize that fear of cannibalism drives their need for safety in numbers. This theory aligns with observations of Transient orcas targeting solitary individuals, especially when food sources are scarce.
The implications of this study highlight the complex social dynamics within the orca community. Cannibalistic behavior among Trans
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Originally published on New Scientist on 2/24/2026