title: Social effects on foraging behavior and success depend on local environmental conditions.
abstract: In social groups, individuals' dominance rank, social bonds, and kinship with other group members have been shown to influence their foraging behavior. However, there is growing evidence that the particular effects of these social traits may also depend on local environmental conditions. We investigated this by comparing the foraging behavior of wild chacma baboons, Papio ursinus, under natural conditions and in a field experiment where food was spatially clumped. Data were collected from 55 animals across two troops over a 5-month period, including over 900 agonistic foraging interactions and over 600 food patch visits in each condition. In both conditions, low-ranked individuals received more agonism, but this only translated into reduced foraging performances for low-ranked individuals in the high-competition experimental conditions. Our results suggest one possible reason for this pattern may be low-ranked individuals strategically investing social effort to negotiate foraging tolerance, but the rank-offsetting effect of this investment being overwhelmed in the higher-competition experimental environment. Our results also suggest that individuals may use imbalances in their social bonds to negotiate tolerance from others under a wider range of environmental conditions, but utilize the overall strength of their social bonds in more extreme environments where feeding competition is more intense. These findings highlight that behavioral tactics such as the strategic investment of social effort may allow foragers to mitigate the costs of low rank, but that the effectiveness of these tactics is likely to be limited in certain environments.
authors.affiliation: Institute of Zoology, Zoological Society of London Regent's Park, London, NW1 4RY, U.K ; Division of Ecology and Evolution, Department of Life Sciences, Imperial College London Silwood Park, Ascot, Berkshire, SL5 7PY, U.K ; Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall, TR10 9EF, U.K.
authors.forename: Harry H
authors.initials: HH
authors.lastname: Marshall
authors.affiliation: Institute of Zoology, Zoological Society of London Regent's Park, London, NW1 4RY, U.K ; The Fenner School of Environment and Society, The Australian National University Acton, Canberra, ACT, 0200, Australia.
authors.forename: Alecia J
authors.initials: AJ
authors.lastname: Carter
authors.affiliation: Institute of Zoology, Zoological Society of London Regent's Park, London, NW1 4RY, U.K ; Division of Ecology and Evolution, Department of Life Sciences, Imperial College London Silwood Park, Ascot, Berkshire, SL5 7PY, U.K.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Ashford
authors.affiliation: Institute of Zoology, Zoological Society of London Regent's Park, London, NW1 4RY, U.K.
authors.forename: J Marcus
authors.initials: JM
authors.lastname: Rowcliffe
authors.affiliation: Institute of Zoology, Zoological Society of London Regent's Park, London, NW1 4RY, U.K.
authors.forename: Guy
authors.initials: G
authors.lastname: Cowlishaw
keywords: Dominance rank; Papio ursinus; Primate; field experiment; social bonds; social tactics