A full understanding of a species' sociality requires knowledge of their specific social motivations. Following social isolation, animals may show general interest in companionship as a buffer for stress or loneliness, but may also be driven to re-establish expectations and dyadic roles with individuals they had been previously separated from. By deconstructing social behavior across experimental manipulations, it may become possible to disentangle these motivational factors. Physical and vocal

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... interactions were recorded from adult female degu dyads during a series of 20 minute reunion sessions across four experiments. Experiments 1 and 2 found that degu interactions increased following isolation, but also increased after dyads were separated without isolation from other conspecifics. Isolation resulted in more early-session interactions, higher allogrooming before rear-sniffing, and a higher ratio of chitter to non-chitter vocalizations. Experiment 3 showed that a non-social, footshock stressor selectively increased early-session interaction, and Experiment 4 revealed high interaction rates between strangers, with more non-chitter vocalizations and late-session rear-sniffing, and reduced pre-rear-sniff allogrooming. A novel, repeated-k-means clustering approach helped to further specify differences in vocalizations between conditions; e.g., "chaff"-type syllables were more common when relationships were new or potentially being renewed. Results suggest that degus are motivated to establish or re-establish expectations with one-another, and these interactions can differ from those associated with the stress of isolation.