The narwhal ( Monodon monoceros ), an iconic whale of remote Arctic waters, is widely known for its long, spiral tusk, which is really an elongated tooth. The tusk, which is predominantly found in males and can grow up to 10 feet long, is one of the most fascinating traits in nature and the inspiration for myths such as the unicorn. It is believed to play a role in competition for mates, including mating displays. The tusk may have others uses and its function is still debated, primarily because few people have observed how these elusive animals use their tusks in the wild.
Limited field observations also means that little is known about many other aspects of the behavior of this highly gregarious Arctic whale, including social and reproductive behaviors, how they adapt to changing environmental conditions, or whether narwhals engage in behaviors that are not linked directly to fitness, like play.
Using drones, researchers from Florida Atlantic University 's Harbor Branch Oceanographic Institute , and Canada's Department of Fisheries and Oceans, in partnership with Inuit communities in Nunavut in Canada's High Arctic, provide the first evidence of narwhals using their tusks in the wild to investigate, manipulate and influence the behavior of Arctic char (Salvelinus alpinus), including delivering sufficient force with their tusks to stun and possibly kill the fish. Researchers captured 17 distinct behaviors, which shed light on the dynamics between the narwhal, its prey and avian competitors.
Results of the study, published in the journal Frontiers in Marine Science, also reveal the first evidence of likely play, specifically exploratory-object play, in narwhals as well as other fascinating insights into narwhal behavior in a changing Arctic. Aspects of the narwhals' actions for example, may also have included social learning, and possibly social instruction and personality differences among individual narwhal. These novel findings further enrich our understanding of narwhals' complex behavior.
Findings also provide the first reports of interactions between narwhal, fish and birds, including attempted kleptoparasitism, a "food thief" situation, among narwhals and glaucous gulls (Larus hyperboreus).
"Narwhals are known for their 'tusking' behavior, where two or more of them simultaneously raise their tusks almost vertically out of the water, crossing them in what may be a ritualistic behavior to assess a potential opponent's qualities or to display those qualities to potential mates," said Greg O'Corry-Crowe , Ph.D., senior author, a research professor at FAU Harbor Branch and a National Geographic Explorer. "But now we know that narwhal tusks have other uses, some quite unexpected, including foraging, exploration and play."
The narwhals exhibited remarkable dexterity, precision and speed of movement of the tusk, and regularly made adjustments to track the moving target. The tusk, especially the tip of the tusk, was used to interrogate and manipulate the target by brief contacts, which typically elicited a response from the fish.
"I have been studying narwhal for over a decade and have always marveled at their tusks," said Cortney Watt, Ph.D., co-author and research scientist and team lead at Fisheries and Oceans, Canada. "To observe them using their tusks for foraging and play is remarkable. This unique study where we set up a remote field camp and spent time filming narwhal with drones is yielding many interesting insights and is providing a bird's eye view of their behavior that we have never seen before."
This research highlights how environmental changes might introduce new interspecies encounters, challenging Arctic species to adapt.
"Our observations provide clear evidence of narwhals chasing fish and using their tusks to interact directly with the fish and to influence the fish's behavior," said O'Corry-Crowe. "Some of the interactions we saw appeared competitive in nature with one whale blocking or trying to block another whale's access to the same target fish, while others may have been more subtle, possibly communicative and even affiliative. None appeared overtly aggressive."
Social behaviors among the whales – such as learning from one another – also suggest that social processes could speed up behavioral adaptation in response to Arctic changes.
"To understand how narwhals are being affected by and adapting to the changing Arctic, field studies using innovative, non-invasive tools like drones are essential to observe them in their natural environment without disturbing them," said O'Corry-Crowe. "Drones provide a unique, real-time view of their behavior, helping scientists gather crucial data on how narwhals are responding to shifts in ice patterns, prey availability and other environmental changes. Such studies are key to understanding the impact of global warming on these elusive animals."
Study co-authors are Maha Ghazal, Mark Gillespie and Luke Storrie, Fisheries and Oceans Canada; and Paul Galvin and Jason Harasimo, World Wildlife Fund, Canada. Watt also is an adjunct professor at the University of Manitoba.
The research was supported by Fisheries and Oceans Canada; FAU Harbor Branch; the National Geographic Society; the World Wildlife Fund Canada; the Nunavut Wildlife Management Board; and Natural Resources Canada's Polar Continental Shelf Program.
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