Social buffering reduces hair cortisol content in black-tailed prairie dogs during reproduction

Stressors activate the hypothalamic-pituitary-adrenal axis which produces glucocorticoid (GC) hormones. Social buffering, the lowering of glucocorticoid secretion with increased social ties, commonly mitigates the stress response following exposure to a stressor. Black-tailed prairie dogs (Cynomys ludovicianus) are ground-dwelling sciurids that vary their social behaviour over time, and provide an exciting opportunity to investigate social buffering and GC production. We observed social behaviours and measured GC hormones in prairie dogs during the spring (reproduction) and summer. We expected social buffering would reduce GC production in the summer, following the stressors experienced during the spring. However, we found social integration and GC deposition were inversely correlated during the spring, which suggests social buffering occurs during the highly stressful period of reproduction, instead of after. Our study shows that the relationship between social behaviour and GC production is context-dependent, and social buffering may be an adaptive strategy in this colonially-living species.