Some of the orcas off North America’s west coast have taken to wearing dead salmon on their heads, resurrecting a curious trend that was first reported in the 1980s.

Local photographers noticed the salmon-wearing orcas last month – and so did researchers. Deborah Giles, science and research director for the non-profit organisation Wild Orca, was observing the marine mammals in South Puget Sound in south-west Washington a few weeks ago. “We saw one with a fish on its head,” she says. “So that was fun –…