Friend or foe? Can harbour seals tell the difference between different kinds of kilIer whales?
I imagine life as a harbor seal might be a bit harrowing. A Bigg’s killer whale could be lurking around any corner, and a harbor seal is one of their favorite meals. But not all killer whales pose a threat. Fish-eating resident killer whales never have harbor seal on the menu!
So if you are a harbor seal, do you flee every single time you hear a killer whale? What if it’s just a harmless fish-eater? Should you waste precious calories running from whales that most certainly will not eat you?
Harbor seals in British Columbia have solved this condundrum. Over time, they have become habituated to the calls of local resident killer whales, and can tell the difference between these calls and the calls of other killer whales that may pose more of a threat, such as Bigg’s killer whales. Scientists discovered this by playing the calls of local resident killer whales to harbor seals; the majority of the seals ignored the calls, going about their business as if nothing had happened. When they played the calls of Bigg’s killer whales, the seals reacted strongly by diving away and fleeing. The scientists also played the calls of resident killer whales from Alaska. These are also harmless, fish-eating whales, but they sound slightly different than the resident killer whales in British Columbia, and the seals would not have heard them before. Upon hearing the unfamiliar resident killer whales, the seals reacted just as strongly as if they had heard Bigg’s killer whales.
This demonstrates that at first, the seals probably reacted to any killer whale call, fish-eating or not. Over time, they likely grew accustomed the chatty calls of the local resident killer whales and learned they did not pose a threat, but still maintained wariness of Bigg’s killer whales and any other killer whale they did not immediately recognize as being “safe.”
Credit: Emma Luck (https://linktr.ee/northern.naturalist)
Deecke, Volker & Slater, Peter & Ford, John. (2002). Selective habituation shapes acoustic predator recognition in harbor seals. Nature. 420. 171-3.