Encounter frequencies and grouping patterns of narwhals in Koluktoo Bay, Baffin Island

The narwhal (Monodon monoceros) is a deep diving cetacean with a strictly Arctic distribution. The challenges associated with the remoteness of narwhals have resulted in a lack of knowledge of its social behaviour requiring direct, systematic observations. Bruce Head, a peninsula at the mouth of Koluktoo Bay (Nunavut), provides an exceptional site in Canada for nearshore observation of narwhals during the summer. In this study, we document the movement, timing and grouping patterns of narwhals observed from Bruce Head and how they relate to environmental factors such as the tide and the circadian cycle. Narwhals travelled in clusters of 1-25 individuals of mixed sex and age class. Narwhals entered the bay in bigger clusters than when they exited it. The clusters were part of herds that comprised up to 642 clusters. Narwhal movement patterns were not randomly distributed in time but did not consistently follow the tidal or circadian cycles across years. Bruce Head could host long-term behavioural studies of narwhals to unravel several unanswered aspects of narwhal biology.