Effects of Tourist and Researcher Presence on Fecal Glucocorticoid Metabolite Levels in Wild, Habituated Sulawesi Crested Macaques (Macaca nigra)

SIMPLE SUMMARY: Ecotourism managers and field researchers often assume that primates residing in ecotourism locations are accustomed to people and therefore are not adversely affected by visitors. We examined the effects of tourist and researcher presence on three groups of critically endangered, wild crested macaques (Macaca nigra) in Tangkoko Nature Reserve, Sulawesi, Indonesia. Tourists visiting Tangkoko have access to macaque groups and can walk into them. Hence, we examined the possible effects of tourists both (1) in the reserve when outside and away from the study groups and (2) within study groups. We analyzed fecal cortisol metabolite levels (FGCM—a hormone that is often elevated when individuals experience stress) from 456 fecal samples (collected from thirty-three adults). When tourists were present in the forest, but not directly among the macaques, FGCM levels in the macaque groups were higher in months with greater tourist numbers. When tourists were within groups, some females displayed FGCM responses typical of acute stress. Male FGCM levels increased with numbers of tourists within the group, but did not change postexposure. FGCM responses to researchers varied by group, sex, and tourist presence. However, the temporal patterning of FGCM responses indicated little evidence of chronic stress from tourism at Tangkoko Nature Reserve. ABSTRACT: Ecotourism managers and researchers often assume that apparently habituated primate groups no longer experience adverse consequences of prolonged exposure to tourists or researchers. We examined the effects of tourists and researchers on fecal glucocorticoid metabolite output (FGCM) in three critically endangered, wild crested macaque (Macaca nigra) groups in Tangkoko Nature Reserve, Sulawesi, Indonesia. We assayed FGCM from 456 fecal samples collected from thirty-three adults. Tourists can walk through and among macaque groups freely. Hence, we examined the possible effects of tourists both (1) in the reserve when away and not interacting with the study groups and (2) when they were present within the macaque groups. Generalized Linear Mixed Model (GLMM) analysis indicated that when tourists were present in the forest, but not directly among the macaques, FGCM levels in the macaque tourism groups were higher in months with more tourists. When tourists were among the macaque groups, some female macaques experienced rises and subsequent postexposure decreases in FGCM levels, consistent with predictions for acute stress. Male FGCM levels increased with tourist numbers within the group. Nevertheless, they were not significantly different from levels during undisturbed or postexposure conditions. FGCM responses related to researchers in groups varied by group, sex, and tourist presence. However, the temporal patterning of FGCM responses showed little evidence of chronic stress from tourism at this site.