Testing for links between face color and age, dominance status, parity, weight, and intestinal nematode infection in a sample of female Japanese macaques

Abstract

Studies of the role of secondary sexual ornaments in mate choice tend to focus on colorful traits in males, but females of many animal species express colorful ornamentation too. Among non-human primates, investigations into the role of female secondary sexual traits as indicators of life history characteristics, reproductive success, and health status have mostly focused on sexual swellings, whereas only few studies have been conducted on the role of facial color. Recent studies on rhesus macaques and mandrills suggested that female ornamentation might provide information about female life history characteristics, but not on disease resistance factors and parasite infection, which have been shown to affect male ornamentation in some non-primate species. In Japanese macaques (Macaca fuscata), females have brightly colored faces that are indicative of their reproductive status. Here, we aimed to determine whether female facial color might also convey information about age, dominance rank, parity, weight, and intestinal nematode infection in free-ranging individuals. We analyzed whether female facial parameters (luminance and redness) were linked to these individual characteristics, using digital photography and data on intestinal parasite infection collected systematically during 1 month for each of seven free-ranging females. We found no evidence to suggest that female facial color is an indicator of any of these measures in Japanese macaques. Considering our small data set, it is still preliminary to draft any clear conclusions. Future studies combining digital, hormonal, parasitological and behavioral data are needed to assess the possible role of female face color on male preferences and mating choice in Japanese macaques.

Play behavior in immature moor macaques (Macaca maura) and Japanese macaques (Macaca fuscata)

“…The JM were studied on Koshima Islet, Miyazaki prefecture, Japan (31°27′N, 131°22′E), an area of approximately 30 ha covered with evergreen broadleaf forest (Duboscq, Romano, Sueur, & MacIntosh, 2016). Our study group (i.e., main group) was well habituated and has been well studied since 1948, through collection of demographic, ecological, behavioral, and life‐history data (Duboscq et al, 2016; Kawai, 1963; Rigaill et al, 2017; Watanabe, 1989, 2008; Yamagiwa, 2010). When the study started, the group consisted of 55 individuals, including 12 male and 24 female adults, 4 female and 3 male subadults, 5 male and 5 female juveniles, and 2 infants, 1 male and 1 female.…”

“…When the study started, the group consisted of 55 individuals, including 12 male and 24 female adults, 4 female and 3 male subadults, 5 male and 5 female juveniles, and 2 infants, 1 male and 1 female. Sex, age, and kin‐relationships were already known (Duboscq et al, 2016; Kurita, Suzumura, Kanchi, & Hamada, 2012; Rigaill et al, 2017; Watanabe, 2008; Yamagiwa, 2010). Although the group lives on an island, this becomes occasionally connected to the mainland, allowing some exchange of individuals between groups.…”

Does male mate choice select for female coloration in a promiscuous primate species?

“…Hindquarter coloration may also contain information about the inter-cycle probability of conception (Rigaill et al, 2019). Lastly, there is some evidence that skin coloration may reflect inter-individual variation (e.g., social rank, weight, but not parity, Rigaill et al, 2017Rigaill et al, , 2019. Pflüger and colleagues (2014) showed that males increased attention toward an experimentally intense red-coloured version of an unknown female face.…”

Does male mate choice select for female colouration in a promiscuous primate species?

“…Hindquarter colouration may also contain information about the inter-cycle probability of conception (Rigaill et al, 2019). Lastly, there is some evidence that skin colouration may reflect inter-individual variation (e.g., social rank, weight, but not parity, Rigaill et al, 2017Rigaill et al, , 2019. Pflüger and colleagues (2014) showed that males increased attention toward an experimentally intense red-coloured version of an unknown female face.…”