Visitor effects on zoo-housed Sulawesi crested macaque (Macaca nigra) behaviour: Can signs with ‘watching eyes’ requesting quietness help?

Abstract

Visiting public can cause changes in the behaviour of zoo-housed primates. These effects, if indicative of stress, can be of welfare concern. However, few options to mitigate visitor effects through modulating visitor behaviour have been explored. Here we evaluated the effects of visitor number and visitor noise level on the behaviour of five UK groups of Sulawesi crested macaques. We also investigated whether visitor behaviour can be effectively modulated through targeted signage requesting visitors to be quiet, and assessed the use of signs incorporating salient ‘watching’ human eyes, novel to a zoo setting, alongside ‘control’ signs lacking eyes.We used scan sampling to collect over 100 h of behavioural observation data, analysis of which indicated that Sulawesi crested macaques were significantly affected by both visitor number and noise level at all five zoos. We found that active behaviours, such as locomotion or foraging, and behaviours identified as negative for welfare, such as vigilance, increased with increasing visitor number and noise levels, whereas resting and social huddling decreased. The extent to which these behavioural changes reflect welfare, particularly the increase seen in active behaviours, is not clear. We also found that both sign treatments, with and without salient eyes, slightly but significantly reduced visitor noise levels compared with no sign, although signs displaying human eyes were not more effective than the control signs.Our results highlight a need for further research into active behaviours to assess whether increases in these behaviours are associated with stress. While we found signage to be a promising tool to mitigate against these visitor effects, our results also suggest areas in which signs incorporating salient human eyes could be adapted for the zoo environment in order to realise their full potential.