Dugatkin and a colleague, Ryan Earley of Georgia State University, studied eavesdropping among male swordtail fish they placed in an experimental tank. They put two fish on one side of a partition and a lone observer male on the other. In some cases, the partitions were clear and in others, opaque.
The fish that could observe their potential adversaries fighting through the clear partition were less likely to defeat the winner of the fight.
"We were able to separate winning and losing streaks based on eavesdropping," Dugatkin says.
Psychological factors such as simply watching a fight seem to have a drastic effect on animal societies and the levels of aggression within them, he adds.
"My own studies indicate that they (psychological factors) can be used to make predictions such as whether interactions between group members will be autocratic or meritocratic ... the same rules may even help explain the dynamics of human societies."
Findings of the experiment were published recently in the Proceedings of the Royal Society of London.
Dugatkin's conclusion about eavesdropping and animal behavior also is included in an article appearing in the Sept. 19, 2002, issue of Nature, "Behavioural ecology: Nosy Neighbors."