Rates of self-directed behaviour and faecal glucocorticoid levels are not correlated in female wild olive baboons (Papio hamadryas anubis)

Abstract

Non-invasive methods to quantify components of stress in non-human animals rely typically on the use of physiological or behavioural measures. At the physiological level, stress is usually measured non-invasively in terms of faecal or urinary glucocorticoid output. A common group of behavioural measures used are self-directed behaviours (SDBs), which have been shown to be linked to anxiety, a subset of stress, although a number of authors have explicitly linked SDBs to stress more generally. Whether increased rates of SDBs are likely to be associated with increased faecal glucocorticoid ouput in wild mammals remains unclear. Here, for wild female olive baboons, we show no association between day-to-day changes in levels of SDB and cortisol metabolite excretion. We also show no relationship between long-term mean levels of these variables. We discuss several possible interpretations of our results, including the possibility that SDBs represent a behavioural coping mechanism, helping to ameliorate the physiological stress response.