The behavioral response and physiological adaptation mechanism of captive sub-adult giant pandas in response to the short-term social environment

During ex-situ conservation, giant pandas inevitably shift from their natural wild habitats to captive settings. The living circumstances of captive giant pandas are strikingly dissimilar from those in the wild. For instance, during the sub-adult stage, solitary giant pandas are reared in groups by humans. What is the influence of the captive social environment on solitary giant pandas? Does it bring about alterations in behavioral expression patterns? Is this pattern associated with physiological responses for environmental adaptation? Or is it a way of maintaining the social structure in solitary animals? To verify our speculation, we divided six giant pandas into a group-housed group and a solitary housed group, with each group consisting of three pandas. By observing their behaviors and conducting analyses of urinary and fecal metabolomics, as well as metagenomics, we intended to explore the welfare status of the two groups under different management modalities. The results demonstrated that group-housed giant pandas exhibited significantly more playing behavior than solitary ones. Further analysis revealed that the majority of the playing behavior involved playful interactions with companions. Additionally, we were pleasantly surprised to discover that no stereotypic behaviors emerged in group-housed giant pandas. Through exploration of the omics data, it was found that urinary metabolites associated with positive emotions, such as dopamine and tryptophan, along with related metabolic pathways like the dopamine synthesis system and tryptophan synthesis pathway, were conspicuously upregulated and activated. Simultaneously, beneficial gut microbiota significantly increased, while harmful bacteria significantly decreased. These results imply that short-term group living indeed has an impact on the behavioral expression patterns of captive sub-adult giant pandas. Furthermore, short-term sub-adult giant pandas housed in groups seem to be happier and experience less stress compared with those kept in isolation. This reveals the physiological and behavioral response mechanisms of captive sub-adult giant pandas to group living environments.