Exploration of grouping characteristics and spatial distribution of beluga whales (Delphinapterus leucas) in the Eastern Beaufort Sea
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Date
2022-03
Authors
Mayette, Alexandra
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Abstract
Beluga whales (Delphinapterus leucas) are considered social whales, but like any other cetaceans, the study of social behaviour is challenging to conduct. Due to the wide distribution of the Eastern Beaufort Sea beluga whale population across its summering grounds, little is known about the large-scale grouping behaviour and spatial distribution of groups. The aim of this research is to explore the grouping characteristics and organization of beluga groups, as well as the habitat preference of different social groups in summer. First, we used aerial photographs captured in July 2019 to describe group size, age composition, inter-individual distance, and swimming direction of beluga groups. We compared characteristics between two key summer habitats: the extended offshore of the Beaufort Sea shelf and the inshore of the Mackenzie Estuary. Results showed that group size and inter-individual distance were similar in both habitats. The average distance in a group varied with age composition and the swimming direction varied between the offshore and inshore. Second, we used GPS locations of beluga sightings recorded by visual observers during aerial surveys conducted in July and August 2019. We investigated the distribution of three beluga social group types (individual belugas, groups of adults, and groups with calf) using hierarchical generalized additive models. The sea surface temperature, bathymetry, and slope described best the summer distribution. Areas of high preference were often associated with prey distribution, suggesting foraging as the main driver of habitat preference. We also hypothesized that body size energy requirements contributed to the variation between the group types. This study revealed for the first-time observations of grouping behaviour in the summer habitat of the Eastern Beaufort Sea beluga whales. Although the results do not reflect the extent and complexity of beluga social behaviour, this study now provides an information baseline for this beluga population. We also encourage multidisciplinary research as an opportunity to further collect data and explore other elements of beluga whale sociality.
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Keywords
Arctic, habitat model, marine mammal, photogrammetry