Mr. Liable: A resident male sperm whale in the Azores?

Abstract

Little is known about the migration routes and lifestyle of male sperm whales around the North Atlantic. Social structure of sperm whales is characterized by female philopatry; forming stable groups through the year and male dispersal. After dispersal, males live in bachelor groups for a few years, becoming more solitary as they age. Mature males spend most of their time in high latitudes, occasionally traveling to low latitudes for breeding. Here we investigate the occurrence of a visually classified mature sperm whale male off Sao Miguel Island, Azores all year around. Our dataset includes sightings and photographs of sperm whales throughout the Azores archipelago obtained from different sources (whale watching platforms, dedicated surveys and others) covering the period of 2010-2017. A basic characterization of the residency patterns for male and female sperm whales in the study area was calculated using the mean monthly sighting rate and the lagged identification rate, to be compared with this specific male. Home range was also calculated using a kernel analysis. A total of 101 sightings for this individual have been recorded since 2010, making him the most observed male off the islands compared to other male encounters. . He has been observed every year of the study period, showing some inter-annual differences and is frequently observed in early winter, when he should be migrating to northern waters according to the classic theory. Moreover, most of the sightings of “Mr. Liable” cluster in a specific area, when comparing to other sperm whales observed in the area, suggesting the existence of a specific spatial residency pattern.

Full text

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16Futurismo Azores6Whale6Watching,6Ponta6Delgada,6Azores,6Portugal.
26Department6of6Applied6Physics,6Universidade de6Vigo,6Vigo,6Spain.
36Centre6for6Ecology, Evolution and6Environmental6Changes6/6Azorean6Biodiversity6Group.6
Faculdade de6Ciências e6Tecnologia,6Universidade dos6Açores.6Ponta6Delgada,6Azores,6Portugal.66
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