Social structure and residency in aggregations of male sperm whales

• Published in: Canadian journal of zoology Vol. 80; no. 7; pp. 1189 - 1196
• Main Authors: Lettevall, Erland, Richter, Christoph, Jaquet, Nathalie, Slooten, Elizabeth, Dawson, Steve, Whitehead, Hal, Christal, Jenny, Howard, Penelope McCall
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.07.2002; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Animal behavior; Animal ethology; Aquatic mammals; behavior; Biological and medical sciences; Biological Sciences; Biologiska vetenskaper; Ecology; Ekologi; Fundamental and applied biological sciences. Psychology; galapagos-islands; kaikoura; Males; Mammalia; Marine; new-zealand; nova-scotia; patterns; photoidentification; Physeter catodon; physeter-macrocephalus; Psychology. Psychoanalysis. Psychiatry; seasonal distribution; Social conditions; Vertebrata; vocalizations; Whales; Whales & whaling; Tropical Pacific Ocean; Europe; Atlantic Ocean; Galapagos Islands; South Pacific; Pacific Ocean Islands; North America; Oceania; New Zealand; Canada; Norway; Nova Scotia; America; Pacific Ocean; North Atlantic; ANE, Norway; PSE, New Zealand; Canada, Nova Scotia; ANW, Canada, Nova Scotia; Ecuador, Galapagos Is; Marine environment; Aggregation; Vertebrata; Mammalia; Social behavior; Geographic distribution; Social structure; Male; Cetacea; Social organization; Physeter macrocephalus
• ISSN: 0008-4301; 1480-3283; 1480-3283; 0008-4301
• DOI: 10.1139/z02-102

Sperm whales (Physeter macrocephalus) are sexually dimorphic in several respects, including size, latitudinal distribution, and social structure. Females are known to have complex social structures, including long-term bonds, but the social structures of sexually mature or maturing males have received much less attention. Using data from aggregations of males off Norway, Nova Scotia, New Zealand, and the Galápagos Islands, we examined aggregation size, residence times within aggregations, clustering at the surface, and long-term bonds. Results were generally consistent among study areas. The aggregations found in each area contained around 10–30 males at any time, and were usually a few tens of kilometres across. Mean residence times within aggregations ranged from a few days to a few weeks. Close clustering at the surface was rare, but present at each site. There was no evidence for preferred companionship between individuals at any temporal scale in any of the study areas. The rarity of clustering and the apparent lack of long-term relationships amongst male sperm whales contrast strongly with results of studies on females, suggesting that both close spatial proximity at the surface and permanent bonds between individuals may be a consequence of the need for care of the young.