A group of killer whales have revived a strange trend from the 1980s of swimming around with dead salmon on their heads.
Scientists observed the whales displaying this unusual activity again off the coast of Washington State in the US, the same region in the Pacific Northwest where the “salmon herd” behavior was last observed 40 years ago.
In 1987, a female killer whale was spotted around Puget Sound with a dead salmon on her nose. The craze then quickly caught on as other orcas began to adopt the same behavior.
The parading stopped as abruptly as it seemed and the 'salmon hats' were gone by 1988.
However, the behavior has returned for reasons as mysterious as why it started in the first place. In recent weeks, orcas have been observed wearing the 'salmon hats' again and placing the dead fish on their heads.
They may even be the same killer whales that adopted this trend in the 1980s, as the species can live up to 100 years in the wild.
Experts are trying to understand exactly why they've returned to a trend that went out of fashion four decades ago.
Orcas are known to carry prey with them, perhaps for later consumption when they become hungry again – YouTube
It may be a form of play behavior or a response to the large number of salmon in the region this year. After feeding on the large schools of salmon until they are full, the whales can carry the dead fish with them until they become hungry again.
Killer whales are known to carry prey with them, perhaps for later consumption.
Deborah Giles, research director at conservation group Wild Orca, told New Scientist: “We've seen mammal-eating killer whales carry large pieces of food under their pectoral fin, sort of tucked next to their body.”
The salmon are too small and slippery to be trapped under a fin, meaning the orcas put them on their heads.
They are known to be highly capable predators that appear to learn behavior from each other. Their intelligence is clearly reflected in the different hunting strategies they employ for different prey in separate parts of the world.
Off the coast of South Africa they will attack great white sharks and remove their livers with large, precise bites.
In Antarctica, they are known for using a wave technique to create waves that knock seals off ice floats into the water, where they are easy prey.
Killer whales are deliberately stranded along the coast of Patagonia in an attempt to capture sea lions.
As the largest member of the dolphin family, male killer whales can weigh up to 9,800 kg or 10 tons and reach a length of 10 meters.
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