One ocean, many killer whale cultures

I’ve marvelled at the killer whales here, but it had never crossed my mind that killer whale culture might differ from place to place. But maybe it does! From Hakai Magazine: One Ocean, Many Killer Whale Cultures.

In the cold, dark waters off the southern tip of Iceland, killer whales work together to corral fish into tight balls, taking turns to stun and devour them. Groups of up to 200 whales will enter the fray, feeding on these concentrated schools of herring. A few months later, some of these same whales will be 1,000 kilometers away, working in small groups to hunt seals along the Scottish coast.

The observation that Icelandic killer whales are fluid in both their choice of prey and their group size surprised researchers studying the whales’ social structure. This behavior, discovered by Sara Tavares of Scotland’s University of St Andrews, was unlike that of the intensively studied killer whales of the northeast Pacific, which have more rigid and hierarchical relationships. There, resident killer whales feed on salmon, stick to relatively small home ranges, and live in stable kinship groups led by a matriarch. In contrast, northeast Pacific transient killer whales are marine mammal specialists that live in small groups and travel over wide ranges. While transients also form family groups, it is not uncommon for individuals to form temporary associations with other transient killer whales. Residents and transients, however, rarely interact.

The findings of Tavares’s team show a much less stable association between Icelandic killer whales. They found that groups frequently break apart and come back together, and that it’s not just the prey type, but how the prey act that may be driving their relationships. [continue]

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