Social organisation and communication of riverine hippopotami in southwestern Kenya

  • Author(s) / Creator(s)
  • In 1982, the population of hippopotami within a 127 km stretch of the Mara River, southwestern Kenya, was in excess of 2800 animals. The average group size was 13.3 individuals; 8 percent adult males, 36 percent adult females, 27 percent subadults, and 29 percent unweaned calves. Males were territorial but abandoned pools during low water conditions, exhibiting little attachment to specific sites. Nursery groups of females and offspring were unstable in composition and moved in response to changing water levels. Responding to seasonal declines in water levels, animals were concentrated in fewer suitable pools. Levels of aggression increased during periods when changing water levels required redistribution of animals but few serious fights were observed. Although interactions between adult males were most striking, the most frequent recipients of aggressive actions were subadults which were commonly expelled from groups. Communication was essential to the establishment and maintenance of dominant/subordinant ranking, both within groups and between individuals encountering each other outside of group situations. Gaping, posturing, and marking defecation were identified as important in the reinforcement of dominance and maintenance of breeding territories by dominant males. There was no strong evidence that behavioural mechanisms played a role in limiting population growth. However, during the course of this investigation there were no identified environmental stresses, such as limited forage availability, imposed upon the population.

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    Article (Published)
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    © 1986 Walter de Gruyter. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited. The final publication is available at
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    • Karstad, E.L. & R.J. Hudson. (1986). Social organisation and communication of riverine hippopotami in southwestern Kenya. Mammalia, 50(2), 153-164. DOI: 10.1515/mamm.1986.50.2.153.