winner loser effectsMathematical models have demonstrated that winner effects (the increased probability of winning your next fight given you won your previous fight) and loser effects (the increased probability of losing your next fight given you lost your previous fight) can lead to highly linear dominance hierarchies even when individuals do not vary in intrinsic fighting ability. Experimentally, studies in many species have demonstrated winner-loser effects when animals of similar size, who have an experimentally induced differential history of winning or losing, are paired together. Working with Dr Tim Fawcett and Dr Sam Ellis from the University of Exeter, UK, we are developing statistical approaches that can identify winner-loser effects in temporally ordered contest data from free-living and captive species. Further, we are interested in identifying how winner-loser effects vary within a social group according to individual traits.