Marine Mammal Research Newsletter


Into the Field

Bowhead rubbing

Sometimes the coolest things happen, when you least expect it.

These four bowhead whales with mottled skin were filmed rubbing their bodies against boulders. Animal A is seen rubbing the right side of its head on a boulder, and Animal D is using the rocks to exfoliate its chin. The long, thin lines running length and width-wise across the body of Animal C were caused by rubbing against rocks. Images captured by VDOS Global LLC

Since grade school, we’ve been taught the importance of applying the scientific method while observing and answering questions about the world around us. This means having clear hypotheses to test—and employing rigorous methods to collect, analyze and interpret data.

But, what happens when things don’t go quite to plan and you stumble upon something that falls completely outside your research scope?

This is what happened during Sarah Fortune’s PhD fieldwork in the remote waters of Cumberland Sound, Nunavut. Sarah and her colleagues had traveled there to study the diet and feeding behavior of Eastern Canada-West Greenland bowhead whales by recording their underwater movements using archival tags and collecting co-located prey data using a suite of oceanographic sampling equipment.

To their amazement, the team found that bowheads don’t just feed in Cumberland Sound, but they also exfoliate here with help of large rocks along the shoreline.

This unexpected observation of whales rubbing their bodies against large rocks gives new insight into the biological significance of Cumberland Sound to the whales — and shows how the coolest things can sometimes happen when you least expect them!


Evidence of molting and the function of rock-nosing behavior in bowhead whales in the eastern Canadian Arctic.
Fortune, S. M. E., W. R. Koski, J. W. Higdon, A. W. Trites, M. F. Baumgartner and S. H. Ferguson. 2017.
PLoS ONE, pages: e0186156 Vol 12(1)
Bowhead whales (Balaena mysticetus) have a nearly circumpolar distribution, and occasionally occupy warmer shallow coastal areas during summertime that may facilitate molting. However, relatively little is known about the occurrence of molting and associated behaviors in bowhead whales. We opportunistically observed whales in Cumberland Sound, Nunavut, Canada with skin irregularities consistent with molting during August 2014, and collected a skin sample from a biopsied whale that revealed loose epidermis and sloughing. During August 2016, we flew a small unmanned aerial system (sUAS) over whales to take video and still images to: 1) determine unique individuals; 2) estimate the proportion of the body of unique individuals that exhibited sloughing skin; 3) determine the presence or absence of superficial lines representative of rock-rubbing behavior; and 4) measure body lengths to infer age-class. The still images revealed that all individuals (n = 81 whales) were sloughing skin, and that nearly 40% of them had mottled skin over more than two-thirds of their bodies. The video images captured bowhead whales rubbing on large rocks in shallow, coastal areas --likely to facilitate molting. Molting and rock rubbing appears to be pervasive during late summer for whales in the eastern Canadian Arctic.
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Sarah Fortune is a PhD Student at UBC’s Marine Mammal Research Unit.

Project Partners: Fisheries and Oceans Canada (Steven Ferguson), World Wildlife Fund Canada (Brandon Laforest), LGL Limited (Bill Koski), VDOS Global LLC (Thomas Seitz), Higdon Wildlife Consulting (Jeff Higdon), Woods Hole Oceanographic Institution (Mark Baumgartner), Pangnirtung Hunter and Trappers Association and Peter’s Expediting & Outfitting Services. 


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