Temperature-based summer habitat partitioning between white-beaked and common dolphins around the United Kingdom and Republic of Ireland

Colin D. Macleod, Caroline R. Weir, M. Begona Santos, Timothy E. Dunn

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The white-beaked dolphin (Lagenorhynchus albirostris) and short-beaked common dolphin (Delphinus delphis) are two of the most abundant delphinid species in shelf waters around the United Kingdom (UK) and Republic of Ireland (ROI) in the summer season (May-October). As these two species have similar habitat preferences and diets, it might be expected that they would partition their otherwise shared niche to reduce the potential for competition at this time of year. This study used 569 sightings of the two species, collected from shelf waters (< 200 m water depth) in the summer season between 1983 and 1998, to investigate whether there is evidence of widespread niche partitioning based on water temperature in this area. Below 13 degrees C, white-beaked dolphins were dominant with 96% of sightings comprising this species. In contrast, above 14 degrees C, 86% of sightings comprised common dolphins. A classification tree analysis found that of the four eco-geographical variables analysed (water depth, seabed slope, seabed aspect and sea surface temperature), temperature was the most important variable for separating the occurrence of the two species. These results are consistent with widespread temperature-based niche partitioning between white-beaked and common dolphins in shelf waters around the UK and ROI. As temperature is important in determining the relative distribution of these species, the range of the white-beaked dolphin might be expected to contract in response to increasing sea temperature resulting from global climate change, while that of the common dolphin may expand.

Original languageEnglish
Pages (from-to)1193-1198
Number of pages6
JournalJournal of the Marine Biological Association of the United Kingdom
Issue number06
Early online date17 Mar 2008
Publication statusPublished - Sep 2008


  • white-beaked dolphin
  • common dolphin
  • water temperature
  • habit partitioning
  • cetacean community
  • marine mammals
  • climate-change
  • Scotland
  • West

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