For some bottle dolphins, finding a meal may be about who you know.
Dolphins often learn to hunt from their mothers. But when it comes to at least one forage trick, Indo-Pacific bottlenose dolphins in Western Australia’s Shark Bay pick up on the behavior of their mates, researchers argue in a report published June 25 in Current Biology.
Although previous studies have suggested that dolphins learn from peers, this study is the first to quantify the importance of social media over other factors, says Sonja Wild, a behavioral ecologist at the University of Konstanz in Germany.
Cetaceans (dolphins, whales, and pompoms) are known to use clever strategies to round meals. Bellows whales (Megaptera novaeangliae) outside Alaska sometimes use their fins and circular bubble nets to catch fish (SN: 10/15/19). In Shark Bay, Indo-Pacific bottlenose dolphins (Tursiops aduncus) use sea sponges to protect their beaks as they take root for food by the sea, a strategy that animals learn from their mothers (SN: 8 / 06/05).
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These Shark Bay dolphins also use a more unusual tool-based foraging method called shelling. A dolphin catches underwater prey in a large sea snail shell, throws its beak into the shell opening, lifts the shell above the surface of the water, and satiates the contents to its mouth.
“It’s a lot of fun,” says Wild, who studied these dolphins as a graduate student at the University of Leeds in England. This brief behavior appears to be rare: From 2007 to 2018, Wild and colleagues documented 42 bombing events of 19 individual dolphins from 5,278 dolphin group encounters in the western Gulf of Shark Bay.
Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia, have a clever method of looking for a snack. A dolphin catches underwater prey in a large sea snail shell, throws its beak into the shell opening, lifts the shell above the surface of the water, and satiates the contents to its mouth. In a recent study, researchers found that dolphins can learn this foraging behavior from their mates.
The researchers analyzed the behavior of 310 dolphins, including 15 refugees, who were seen at least 11 times. The network of dolphins ’social interactions explained that wear and tear extends better than other factors, including the genetic relationship and the amount of environmental overlap between dolphins. Wild shows the proliferation of this behavior with the spread of a virus. “Only by spending time with each other (dolphins) are they more likely to transmit those behaviors,” he says. Researchers estimate that 57 percent of dolphins that shell learned the skill through social transmission, rather than on their own.
But researchers may be premature in dismissing environmental and maternal factors, says Janet Mann, a biologist at Georgetown University in Washington, D.C., who also studies the behavior of dolphins in Shark Bay. The environment affects where wear and tear can occur. “These shells are found in particular habitats and animals that overlap in these habitats would have access to those shells, but they also hit each other more often,” he says. The behavior of striking a dolphin may also have been influenced during the tens of thousands of hours the animal spent as a young man looking at its mother.
“Dolphins are smart: they look at each other and see what others do,” she says.