Effects of cortisol administration on cooperative behavior in meerkat helpers

Abstract

Although the ultimate causes for variation in contributions to helping in cooperative breeders are increasingly well understood, the underlying physiological mechanisms remain largely unknown. Recent work has suggested that glucocorticoids (GC) may play an important role in the expression of cooperative behaviour. Here, we present the first experimental test of the effects of GCs on helper behaviour in a cooperative breeder. GC levels of adult female and male meerkat helpers were elevated with an intra-muscular injection of cortisol (hydrocortisone 21hemi-succinate sodiumsalt) dissolved in saline, whilst matched controls simultaneously received an injection of saline. There were no changes in pup feeding or sentinel behaviour, but females spent more time in close proximity to pups and less time foraging when GC levels were elevated. These results provide no evidence that GCs affect cooperative behaviour, but suggest that there may be an effect on affiliation with pups and foraging effort.