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Trade-offs of predation and foraging explain sexual segregation in African buffalo

1.Many studies have investigated why males and females segregate spatially in sexually dimorphic
species. These studies have focused primarily on temperate zone ungulates in areas lacking intact
predator communities, and few have directly assessed predation rates in different social environments.
2.Data on the movement, social affiliation, mortality and foraging of radio-collared African
buffalo (Syncerus caffer)
were collected from 2001–06 in the Kruger National Park, South Africa.
3.The vast majority of mortality events were due to lion (Panthera leo)
predation, and the mortality hazard associated with being an adult male buffalo in a male-only ‘bachelor’ group was almost four times higher than for adult females in mixed herds. The mortality rates of adult males
and females within mixed herds were not statistically different. Mortality sites of male and female buffalo were in areas of low visibility similar to those used by bachelor groups, while mixed herds
tended to use more open habitats.
4.Males in bachelor groups ate similar or higher quality food (as indexed by percentage faecal nitrogen), and moved almost a third less distance per day compared with mixed herds. As a result,
males in bachelor groups gained more body condition than did males in breeding herds.
5.Recent comparative analyses suggest the activity-budget hypothesis as a common underlying cause
of social segregation. However, our intensive study, in an area with an intact predator community
showed that male and female buffalo segregated by habitat and supported the predation-risk hypothesis. Male African buffalo appear to trade increased predation risk for additional energy
gains in bachelor groups, which presumably leads to increased reproductive success.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1000454
Date January 2008
CreatorsHay, CT, Cross, PC, Funston, PJ
PublisherBritish Ecological Society
Source SetsSouth African National ETD Portal
LanguageEnglish
Detected LanguageEnglish
TypeText
FormatPDF
RightsJournal of Animal Ecology
RelationJournal of Animal Ecology

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