Eastern water dragons use alternative social tactics at different local densities

摘要

Animals’ affiliative behaviour is, in many species, driven by population density. Although the causes of such an effect are probably varied, affiliative social behaviour can sometimes be used to minimise conflict and competition when conspecific density is high. However, individuals might instead use multiple different social tactics (e.g. social avoidance or social preference) in order to optimally minimise competition and social conflict at different local densities. Here, we investigated whether eastern water dragons ( Intellegama lesueurii ) use alternative social tactics at different local densities. Interestingly, we found that whilst the number of casual associations per individual increased linearly with density, as predicted by our null expectation, the relationship with density differed between social avoidance and social preference. In particular, individuals had more preferential associations at intermediate density but more avoidances at high density. This suggests that both male and female dragons use alternative social tactics according to the density of their social environment, possibly to optimally reduce social conflict. Significance statement This study investigated the relationship between local density and social tactics (e.g. social preference and social avoidance) in eastern water dragons. We demonstrate that dragons use different social tactics according to local density. We therefore present evidence that dragons may use alternative social tactics to optimally reduce competition and conflict in their local environment.