Killer whales off the coast of Washington State have been seen balancing salmon carcasses on their heads, a behavior that dates back decades, but researchers are still uncertain why they do this.
Killer whales in the Northwest Pacific have resumed the peculiar practice of wearing salmon hats, a trend first documented in the 1980s. Last month, scientists and whale watchers spotted killer whales (Orcinus orca) in the South Puget Sound and off Point No Point in Washington State swimming with salmon carcasses on their heads, as reported by Live Science on November 27.
Killer whales have resumed the trend of wearing salmon carcasses on their heads. (Photo: Tory Kallman).
This is the first time these whales have donned such a strange accessory since the summer of 1987, when a female killer whale on the West Coast initiated the behavior for reasons that remain unclear. Within two weeks, other members of the pod began to mimic her, turning salmon carcasses into a synchronized fashion statement, according to the marine conservation charity ORCA. However, researchers are unsure if a similar phenomenon is happening this time around.
Researchers believe that killer whales wearing salmon hats may have once participated in this trend when it first emerged nearly 40 years ago. “It’s possible that some individuals who originally displayed this behavior are doing it again,” said Andrew Foote, an evolutionary ecologist at the University of Oslo in Norway.
The motivation behind the salmon hat trend remains a mystery, according to Deborah Giles, a killer whale researcher at the University of Washington. Salmon hats are a prime example of a “fad,” behavior that originates from one or two individuals and is temporarily adopted by others before being forgotten. In the 1980s, this trend lasted only a year. By the summer of 1988, the salmon hats had disappeared from the population of killer whales on the West Coast.
Researchers speculate that the behavior of wearing salmon hats is likely related to food availability. The South Puget Sound is currently teeming with chum salmon (Oncorhynchus keta). With an abundance of food available, killer whales may be saving fish for later by balancing them on their heads.
Killer whales have also been observed storing food in other ways. Giles and her colleagues have witnessed killer whales carrying large pieces of food under their pectoral fins and tightly wedged against their sides. Salmon may be too small to hold securely under the pectoral fins, so they have opted to carry them on their heads instead.
Drones equipped with cameras can help researchers monitor killer whales wearing salmon hats in a more feasible way than was possible 37 years ago. Over time, Giles’s team may gather enough information to reveal how long an individual carries a salmon carcass before eating it. However, the hypothesis about food availability could be disproven if footage reveals that killer whales are not eating the salmon.
