Communication networks and loser effects interact to influence the outcome of aggressive interactions in the crayfish Orconectes rusticus

Dyadic interactions occur in the vicinity of non-participating animals such that bystanders have the potential to extract relevant information about future opponents. Individuals within communication networks can use information to modify their behaviour in future encounters with a previous fighter. Previous research on crayfish (Orconectes rusticus) has shown that watching fights negatively impacts the ability of bystanders to win against naive opponents. We examined the role of visual information in communication networks and previous social history, in the form of winner and loser effects, in shaping crayfish aggression and outcomes of aggressive encounters. Experimental treatments consisted of allowing a bystander to observe a fight and then engaging that bystander with either the winner or loser in a subsequent encounter. Our results indicate that previous social history is more influential in determining fight outcome than information gathered via visual signals. Specifically, loser effects have a greater influence on fight dynamics than elements of communication networks. Since crayfish use a combination of sensory cues during social interactions, visual information may not provide the proper context for information use in subsequent interactions. We conclude that previous social history may be masking any effects that visual communication networks have on agonistic behaviour in crayfish.