Within-group spatial position and vigilance: a role also for competition? The case of impalas (Aepyceros melampus) with a controlled food supply

@article{Blanchard2008WithingroupSP,
  title={Within-group spatial position and vigilance: a role also for competition? The case of impalas (Aepyceros melampus) with a controlled food supply},
  author={Pierrick Blanchard and Rodolphe Sabatier and Herv{\'e} Fritz},
  journal={Behavioral Ecology and Sociobiology},
  year={2008},
  volume={62},
  pages={1863-1868}
}
Theory predicts that individuals at the periphery of a group should be at higher risk than their more central conspecifics since they would be the first to be encountered by an approaching terrestrial predator. As a result, it is expected that peripheral individuals display higher vigilance levels. However, the role of conspecifics in this “edge effect” may have been previously overlooked, and taking into account the possible role of within-group competition is needed. Vigilance behavior in… 

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References

SHOWING 1-10 OF 30 REFERENCES
COSTS AND BENEFITS OF WITHIN‐GROUP SPATIAL POSITION: A FEEDING COMPETITION MODEL
  • B. Hirsch
  • Biology, Medicine
    The Quarterly Review of Biology
  • 2007
TLDR
A qualitative model is presented here to predict how food depletion time, abundance of food patches within a group, and the presence of prior knowledge of feeding sites affect the payoffs of different within‐group spatial positions for dominant and subordinate animals.
Group-size and distance-to-neighbour effects on feeding and vigilance in brown-headed cowbirds
TLDR
The strength of the group-size effect varied with neighbour distance and was weakest when the birds were furthest away from each other, which suggests future studies should consider as members of a group only those individuals within a radius that allows detection and dilution effects to operate.
PREDATOR VIGILANCE AND GROUP SIZE IN MAMMALS AND BIRDS: A CRITICAL REVIEW OF THE EMPIRICAL EVIDENCE
  • M. Elgar
  • Psychology, Medicine
    Biological reviews of the Cambridge Philosophical Society
  • 1989
TLDR
Most of the studies fail to adequately demonstrate an unambiguous relationship between vigilance behaviour and group size, but many studies reveal interesting features of the relationship between Vigilance and Group size that should provide fruitful avenues for future research.
SIZE-RELATED EFFECTS ON SEARCH TIMES IN NORTH AMERICAN GRASSLAND FEMALE UNGULATES'
TLDR
The hypothesis that body mass alone accounts for interspecific differences in search times is examined, and the importance of designing field research that controls for con- founding variables prior to attempting to scale behavioral processes to ecological events is highlighted.
DIFFERENTIAL FITNESS RETURNS IN RELATION TO SPATIAL POSITION IN GROUPS
  • Jens Krause
  • Biology, Medicine
    Biological reviews of the Cambridge Philosophical Society
  • 1994
TLDR
A general overview of position-related fitness differences in group-living animals is given for the first time and it is suggested that edge positions achieve a higher net-energy pay-off and should therefore be preferred by individuals with low energy reserves.
Vigilance Behaviour in Grazing African Antelopes
TLDR
Time spent looking varied with position within the group; this effect was strongest in closed habitats, where central animals tended to scan least and feed most, and within species, animals inclosed habitats, those with dense vegetation, tended to spend more time in looking than did animals in the open.
Antipredator vigilance in birds: modelling the 'edge' effect.
TLDR
A vigilance model is described which investigates the effect of position on the birds' strategies by dividing the feeding area into an inner and outer region and predicts that birds in the outer group are always more vigilant than those in the inner region.
Foraging costs of vigilance in large mammalian herbivores
TLDR
Behavior observations to evaluate whether vigilance decreases the bite rate of free-ranging female bison in Prince Albert National Park and elk in Yellowstone National Park observed that vigilance induced foraging costs, but these costs were less important than traditionally assumed.
Red kangaroos (Macropus rufus) receive an antipredator benefit from aggregation
TLDR
Red kangaroos directly translated the reduction of predation risk brought about by aggregation into greater time foraging and less time engaged in vigilance, inferring that red kangarooos received a net benefit by aggregation.
Marginal predation methodologies and the importance of predator preferences
Correspondence: T. Stankowich, Psychology Department, Young Hall, One Shields Avenue, University of California, Davis, CA 95616, U.S.A. (email: tstankowich@ucdavis.edu). Biologists have studied group
...
1
2
3
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