Sociability increases survival of adult female giraffes |
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Authors: | M L Bond D E Lee D R Farine A Ozgul B Knig |
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Institution: | 1.Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland;2.Wild Nature Institute, Concord, NH, USA;3.Department of Biology, Pennsylvania State University, University Park, PA, USA;4.Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany;5.Center for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany |
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Abstract: | Studies increasingly show that social connectedness plays a key role in determining survival, in addition to natural and anthropogenic environmental factors. Few studies, however, integrated social, non-social and demographic data to elucidate what components of an animal''s socio-ecological environment are most important to their survival. Female giraffes (Giraffa camelopardalis) form structured societies with highly dynamic group membership but stable long-term associations. We examined the relative contributions of sociability (relationship strength, gregariousness and betweenness), together with those of the natural (food sources and vegetation types) and anthropogenic environment (distance from human settlements), to adult female giraffe survival. We tested predictions about the influence of sociability and natural and human factors at two social levels: the individual and the social community. Survival was primarily driven by individual- rather than community-level social factors. Gregariousness (the number of other females each individual was observed with on average) was most important in explaining variation in female adult survival, more than other social traits and any natural or anthropogenic environmental factors. For adult female giraffes, grouping with more other females, even as group membership frequently changes, is correlated with better survival, and this sociability appears to be more important than several attributes of their non-social environment. |
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Keywords: | social network analysis survival giraffe Giraffa camelopardalis fission– fusion society |
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