Behaviour 2019
The cost of interactions dictates strategic investment in dominance interactions
Tobit Dehnen1,2,3, Danai Papageorgiou22,3,4,5,, Brendah Nyaguthii66,7,8, Wismer Cherono7, Julia Penndorf4,9, Neeltje J. Boogert1, Damien R. Farine2346. 1Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom; 2Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, , Switzerland; 3Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, , Germany; 4Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, , Germany; 5Kenya Wildlife Service, Nairobi, , Kenya; 6Department of Ornithology, National Museums of Kenya, Nairobi, , Kenya; 7Mpala Research Center, Nanyuki, , Kenya; 8University of Eldoret, School of Natural Resource Management, Department of Wildlife, Eldorat, , Kenya; 9Cognitive and Cultural Ecology Research Group, Max Planck Institute for Animal Behavior, Radolfzell, , Germany

Dominance rank is important for access to resources. As dominance interactions are costly, individuals should be strategic in who they interact with. One hypothesis is that individuals should direct costly interactions towards those closest in rank, as they have most to gain—in terms of maintaining dominance—from winning such interactions. Here, we test whether higher-cost interactions—fights or chases—are directed more strategically than lower-cost interactions—displacements or submissions—in male vulturine guineafowl (Acryllium vulturinum), a gregarious species with steep dominance hierarchies. We further test whether males are more strategic pre-breeding when competition for access to reproductive females increases. We show that higher-cost interactions are strategically directed towards males occupying ranks immediately below themselves relative to lower-cost interactions. However, we found no evidence for seasonal changes in strategy. Our results support the hypothesis that the costs associated with different interaction types can determine dominance interaction strategies.