From invertebrates to mammals, social behavior plays a fundamental role in the survival of species throughout the animal kingdom. In order to take advantage of past interactions with conspecifics, the brain has to encode, consolidate and recall social memories. Recent findings suggest that the hippocampal region CA2 is essential for social memory, but the nature and the stability of information stored in this circuit remains enigmatic. I will utilize the Egyptian fruit bat, a highly social mammal which develops long-term social networks within the colony, to ask how the long-term and dynamic representation of social information is encoded in CA2. I will adopt advanced behavioral measurements combined with machine learning methods to monitor and characterize social interactions and their associated vocalizations within a natural colony of bats over long periods. To investigate the existence and properties of social coding in CA2, I will take advantage of chronic wireless calcium-imaging in freely behaving and flying bats during behaviorally relevant social interactions as well as during sleep. By combining an ethological approach with cutting edge technologies for detailed measurements of long-term behavioral and neural dynamics, I will aim to uncover fundamental properties of social cognition in the mammalian brain.