A new method for studying social eavesdropping using male golden hamsters.

Social eavesdropping is a special type of social learning and it is defined as the act of extracting information from social interactions between conspecifics. Social eavesdropping has advantages in information gathering and has attracted increasing attention. Emerging studies on social eavesdropping have been reported in several species, but the lack of suitable and manipulable laboratory rodent models remains a challenge to the study of the underlying mechanisms of social eavesdropping. The aim of this study was to take advantage of golden hamsters and their agonistic behaviors to develop a new laboratory method to study social eavesdropping. Male hamsters with or without a defeat experience were used as bystanders and were exposed to either a fighting interaction or a neutral encounter between two male demonstrators in a social learning chamber for a 3-day social learning. The behavioral responses of the bystanders toward observed demonstrators were tested in a U-shaped maze before and after the 3-day social learning. We found that (1) bystanders were attracted to the winning demonstrators in both short-term and long-term tests in experiment 1; (2) bystanders with a brief defeat experience displayed the opposite behavioral pattern and avoided approaching the winning demonstrator in experiment 2. It is evident that these hamsters acquired information about the relative qualities and dominance of the demonstrators and behaved differently toward different conspecifics afterward. Collectively, male hamsters are capable of social eavesdropping and prior experience of defeat has a significant impact on their consequent behaviors. Our newly developed behavioral method offers several advantages and it is useful for the study of social eavesdropping and its underlying mechanisms.