The rare clicking, whizzing, and buzzing sounds of Greenland’s elusive narwhal population is helping to provide insight into how these unicorns of the sea spend their lives in the frigid Arctic waters located between Greenland and Canada.
Monodon Monoceros is a small whale famous for its spiral tusk that reaches lengths of up to 3 meters (10 feet) long. The notoriously shy whales live in the extreme, remote waters of the Arctic Ocean, which have made them exceedingly difficult to study. Researchers with the American Geophysical Union and Hokkaido University have been working the last few years near Bowdoin Glacier in Baffin Bay, a narwhal “hot spot” known for its dramatic calving events, studying the sounds made by glaciers.
“I realized working in the area and not paying attention to the elephant in the room – the key endemic legendary Arctic unicorn just flowing around our glacier – was a big mistake,” said Evgeny Podolskiy, a geophysicist at Hokkaido University in Sapporo, Japan, in a statement.
The team paired up with Northwest Greenland Inuit whale hunters in July 2019, whose close relationship with the cetaceans has allowed them to get closer to the animals. Small underwater microphones known as hydrophones were attached to boats that came as close as 25 meters (80 feet) to record the social calls and foraging sounds of the narwhals. The results are published in the Journal of Geophysical Research: Oceans.
Hydroacoustic data and GPS records indicated that the narwhals come within 1 kilometer (0.6 miles) of calving glaciers – one of the noisiest places in the ocean – as they forage for food.
“There is so much cracking due to ice fracturing and bubbles melting out… it’s like a fizzy drink underwater,” Podolskiy said. “It seems we are dealing with animals living in one of the most noisy environments without having much trouble with that.”
More than 17 hours of recording further captured the various sounds that the cetaceans use to communicate with one another in search of prey: click trains and bursts (or buzzes), pure tones in the form of whistles, and pulsed tones. In some instances, the animals were recorded quickening their clicks until the sound became a chainsaw-like buzzing, helping the whales to find their baitfish prey through echolocation.
“Their world is the soundscape of this glacial fjord,” said Podolskiy. “There are many questions we can answer by listening to glacier fjords in general.”
Amidst the noisy seascape, scientists also picked up on anthropogenic noises like those caused by boat engines, as well as sounds caused by ice melt and cracking noises. Together, the recordings provide researchers with a baseline of the many sounds that make up the narwhal’s “highly susceptible” existence, illuminating poorly understood behaviors and habitats.