Mean fecal glucocorticoid metabolites are associated with vigilance, whereas immediate cortisol levels better reflect acute anti-predator responses in meerkats

Abstract

Adrenal hormones likely affect anti-predator behavior in animals. With experimental field studies,we first investigated associations betweenmean fecal glucocorticoidmetabolite (fGC) excretion and vigilance andwith behavioral responses to alarm call playbacks in free-ranging meerkats (Suricata suricatta). We then tested how vigilance and behavioral responses to alarm call playbacks were affected in individuals administered exogenous cortisol.We found a positive association between mean fGC concentrations and vigilance behavior, but no relationship with the intensity of behavioral responses to alarm calls. However, in response to alarm call playbacks, individuals administered cortisol took slightly longer to resume foraging than control individuals treatedwith saline solution. Vigilance behavior,which occurs in the presence and absence of dangerous stimuli, serves to detect and avoid potential dangers,whereas responses to alarmcalls serve to avoid immediate predation.Our data show that mean fGC excretion in meerkatswas associatedwith vigilance, as a re-occurring anti-predator behavior over long time periods, and experimentally induced elevations of plasma cortisol affected the response to immediate threats. Together, our results indicate an association between the two types of anti-predator behavior and glucocorticoids, but that the underlyingmechanismsmay differ. Our study emphasizes the need to consider appropriatemeasures of adrenal activity specific to different contextswhen assessing links between stress physiology and different anti-predator behaviors.