Site fidelity, social structure and spatial distribution of Short-Finned Pilot Whales, Globicephala macrorhynchus, off the South West Coast of Tenerife

  • Lauren Hartny-Mills

Student thesis: Doctoral Thesis


The conservation management of wild cetaceans depends on knowledge of their population structure and dynamics, and how human activities impact upon resource use and behaviour. The short-finned pilot whale (Globicephala macrorhynchus) is believed to possess a complex social structure, with a high degree of bonding among familial group members that results in natal group philopatry. As the subject of intense tourism activity, the pilot whale population around the Atlantic island of Tenerife was studied to determine spatial distribution, the degree of site fidelity, and the social structure from 2005-2008, using behavioural data and a photo-identification image database consisting of ca. 55,000 photographs compiled by citizen scientists.

There were 382 well-marked individuals identified, which varied in the degree of site fidelity from those encountered throughout the study period to those that were only seen once. At least 22 individuals were matched to a previous study, demonstrating residency spanning 19 years. The distribution of whales in the study area was not random or uniform, and higher rates of encounter occurred offshore at depths of 800-2100 m. The area is important for breeding, calving and foraging, with a core area measuring 99.1 km2 identified.

Social analyses, based on the associations of photo-identified individuals, suggested that the study area contains groups of animals with long-term, constant relationships, with 11 longitudinally stable social clusters identified using hierarchical cluster analysis. However a large proportion of the population forms short-term bonds or has no apparent affiliation with other conspecifics.

Future studies should focus on increasing the extent of study area as the full ranging behaviour of the pilot whales may not have been encompassed here. The long-term site fidelity and stable relationships demonstrated in this island-associated population, may need to be more closely monitored, given the increasing concerns about anthropogenic disturbance in the Canary Islands.
Date of AwardMay 2015
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorTrevor John Willis (Supervisor) & Simon Cragg (Supervisor)

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