(Image credit: Left: Wirestock/Getty Images; Right: Winfried Wisniewski/Getty Images)
Scientists say killer whales in the Pacific Northwest have started wearing salmon hats again, reviving a bizarre tradition first noticed in the 1980s.
Last month, researchers and whale watchers spotted killer whales (Orcinus orca) in South Puget Sound and Point Noe Point in Washington floating with dead fish on their heads.
It's the first time they've worn the unusual headgear again since the summer of 1987, when a female West Coast orca began the behavior for no apparent reason. Within weeks, the rest of the pod had picked up the trend, turning salmon carcasses into must-have fashion items, according to marine conservation nonprofit ORCA — though it's unclear whether the phenomenon will happen again.
Researchers believe that the orcas currently sporting salmon hats may be members of the same group as those observed doing the behavior nearly 40 years ago. “It’s possible that some of the individuals that first experienced [the behavior] may have started doing it again,” Andrew Foote, an evolutionary ecologist at the University of Oslo in Norway, told New Scientist.
The reason for this salmon hat craze remains a mystery. “Honestly, your guess is as good as mine,” Deborah Giles, a killer whale researcher at the University of Washington who also runs science and research projects at the nonprofit Wild Orca, told New Scientist.
Salmon hats are a prime example of what scientists call a “fad” — a behavior that is initiated by one or two individuals and temporarily picked up by others before being forgotten. In the 1980s, the trend lasted only a year; by the summer of 1988, the dead fish were out of fashion entirely, and salmon hats disappeared from the West Coast orca population.
Orca researchers speculate that the salmon hat craze may be linked to high food availability. South Puget Sound is currently teeming with chum salmon (Oncorhynchus keta), and because food is plentiful, orcas may be storing the fish for later by balancing them on their heads, New Scientist reports.
Killer whales have also been observed hiding food in other places. “We’ve seen killer whales holding large pieces of food under their pectoral fins, sort of tucked close to their bodies,” Giles said. Salmon are likely too small to fit securely under the whales’ pectoral fins, so the marine mammals may have chosen the tops of their heads.
Camera-equipped drones could help scientists track salmon-hatted killer whales in a way that wasn’t possible 37 years ago. “In the future, we might be able to collect enough data to show that, for example, one of them carried a fish for about 30 minutes and then ate it,” Giles said.
However, the food availability theory may be wrong – if the video shows the killer whales abandoning the salmon without eating it, the researchers will have to go back to the beginning.
Whatever the reason for the behavior, Giles said it was interesting to see it come back into fashion. “It’s been a while since I last saw it,” she added.
Sourse: www.livescience.com
