The ecological benefits of interceptive eavesdropping

1Eavesdropping behaviour can increase the total amount of information available to an individual and therefore has the potential to provide substantial benefits. Recent research has suggested that some species are information givers', particularly social species with cooperative vigilance systems, and that these species may consequently affect community structure by influencing the behaviour and niche utilization of other species. Here, using behavioural observations and playback experiments, we compared the behavioural change in a solitary species (the scimitarbill) and a social species (the pied babbler), to the presence and alarm calls of one another. Our results revealed that scimitarbills underwent significant behavioural changes in the presence of social pied babblers: they reduced their vigilance rate by over 60%, increased their foraging efficiency and expanded their niche by moving into open habitat and excavating subterranean food items. In contrast, pied babblers - who have an effective intraspecific sentinel system - did not show significant behavioural changes to the presence or alarm calls of scimitarbills. These results suggest that interspecific interceptive eavesdropping can provide significant benefits, influencing the behaviour and habitat utilization of eavesdropping species.