Non-invasive monitoring equipment is incredibly important to underwater scientific discovery. Placed in hard-to-monitor areas, these devices silently and invisibly record sounds to help scientists understand and protect marine life.
Narwhals — the elusive, unicorn-tusked whales of the Arctic — may not be as oblivious to these monitoring devices as researchers previously believed. In a new study, published in Communications Biology, scientists recorded hundreds of narwhal interactions with underwater monitoring devices, revealing that acoustic recording might not be as hands-off as it seems.
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Curious Narwhals Love Underwater Research Gear
The underwater microphones, or hydrophones, used in the study are designed to quietly listen rather than interfere with surrounding marine life.
“Using passive acoustic monitoring to detect acoustically active animals helps to census biodiversity, understand animal behavior and habitat use, and reduce the negative impacts of human-made noise,” explained Evgeny A. Podolskiy from the Arctic Research Center at Hokkaido University, in a press release.
Although the hydrophones are meant to remain undetected, the local narwhals had other plans.
Over a two-year study in northwest Greenland’s Inglefield Bredning Fjord, researchers working alongside local Inughuit hunters deployed three hydrophones between about 623 feet and 1312 feet (190 and 400 meters) deep. What they captured wasn’t just the beauty of Arctic soundscapes, but the distinct “knock” and “buzzes” of narwhals repeatedly investigating the equipment.
In over 4,000 hours of audio, the team counted 247 incidents of narwhals hitting the devices. Accounting for gaps in recording times, researchers estimate that there may have been as many as 600 hits, an average of 10 to 11 per day, and usually during daylight hours.
Why Are Scientists Interested in Narwhals?
Narwhals are known for their long, spiraled tusks and for being among the most mysterious marine mammals on Earth. Living year-round in the ice-filled waters of the Arctic, they use echolocation to navigate and hunt in the darkness.
Though they still remain a mystery to science, the Inughuit hunters who helped deploy and retrieve the hydrophone devices used in the study are well acquainted with these whales’ curious nature.
“Inughuit hunters were not surprised by the discovered interaction: they are familiar with narwhal entanglement in unattended gear,” said Podolskiy. “They also believe narwhals like to play and are told so by their parents, and joked that narwhals might scratch their backs, like cats.”
To understand why the whales were so drawn to the devices, the researchers also analyzed the stomach contents of 16 narwhals caught as part of the community’s subsistence harvesting. They found diets rich in cod, shrimp, and squid. The team suspects that the narwhals may have mistaken the listening devices for prey, though it’s also possible they were simply too curious.
Why Narwhal Curiosity Matters for Arctic Research
For scientists studying life under the ice, passive acoustic monitoring is a crucial tool. These microphones can record for months at a time, offering insights into animal communication, migration, and the soundscape of a rapidly changing Arctic ecosystem.
But if the animals being studied are drawn to the devices, it complicates the idea that this research method is truly non-intrusive. The findings suggest that scientific infrastructure may subtly influence animal behavior, even when it’s designed to observe quietly.
“Understanding animals’ interaction with industrial and scientific infrastructure can help reduce impacts on wild animals and improve our ability to implement and interpret autonomous field observations,” concluded Podolskiy.
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