“Walruses are able to clap underwater so hard that the water between their flippers vaporizes into a cloud of bubbles, which then collapse onto themselves to produce an extremely loud sound,” David Hocking, a senior curator of vertebrate zoology at the Tasmanian Museum and Art Gallery, who was not involved with the research, wrote in an email. Dr. Hocking observed similar clapping behavior in wild gray seals during breeding season, and hypothesized that it was a demonstration of strength and fitness to rivals and potential mates.
The authors of the new study believe Sivuqaq’s clapping has a similar function, because the walrus started clapping as he approached sexual maturity and the behavior was often accompanied with a visible erection. “I think it’s hard for these animals to suppress,” Dr. Reichmuth said, referring to Sivuqaq’s cacophonous drive to breed.
Sivuqaq clapped in an unshakable tempo: 1.2 seconds between claps, the same tempo as the knock sounds he emitted. And his claps were loud; perceptible to humans standing yards away from the four-inch-thick glass walls of his tank. But Sivuqaq’s sounds never reached the full complexity of wild walruses’ breeding displays, which can consist of long patterned sequences of pulses varying in length and punctuated by bell-like sounds, according to a 2003 study. In Dr. Reichmuth’s eyes, the captive walrus produced song components but could not produce complex songs if denied the ability to listen to and learn from other adult walruses’ sounds.
With a data set of one walrus, it’s hard to know whether wild walruses clap, too. “Is this something that one male did? Is it a new way of producing a functionally similar behavior?” asked Eduardo J. Fernandez, an animal welfare scientist at the University of Adelaide, Australia, who was not involved with the research. “For this walrus, it seems to be related to a breeding display,” he said.
Dr. Reichmuth and Dr. Larsen are working on a paper analyzing the biological mechanisms behind Sivuqaq’s other, more familiar breeding sounds — what they originally came to Six Flags to study.