Overmarking by adult females in four equid species: social bonds and group cohesion

Abstract

Scent marking by overmarking deposits made by conspecifics has been well studied in male mammals, but this phenomenon remains poorly understood and rarely studied in females. Furthermore, in socially living mammals like most ungulate species many of the established hypotheses cannot be applied, leaving the function of female overmarking unexplained. In this study, we suggest and test a novel hypothesis: maintenance of social bonds. We examined the occurrence of adult female overmarking in equids and test three classical hypotheses which may explain this phenomenon: group cohesion, intrasexual competition and social hierarchy. We observed all African equid species (Equus africanus, E. grevyi, E. quagga, E. zebra) in five zoos. In total, we recorded 4668 eliminations by 130 individuals; 327 of these events were overmarked by 69 individual females representing all species. Adult females overmarked individuals of each age and sex category, but mostly other females and foals. The rate of overmarking within a dyad of adult females increased with increasing 'friendship' of the dyad, thus demonstrating for the first time that overmarking can serve to support social bonds in mammals. In addition, we found a higher overmarking rate among females in the temporary absence of a stallion than in his presence suggesting partial support for the group cohesion hypothesis. On the other hand, we found no evidence supporting hypotheses of intrasexual competition and social hierarchy. We suggest that the use of overmarking to maintain social bonds may be more important in mammals like equids that live in groups of unrelated individuals.

Avoiding visitors to a protected area increases predation risk for the endangered mountain gazelle

“…We found that gazelles visited scent-marking stations closer to visitors' infrastructure less frequently. Scent-marking stations serve not only for male territorial marking (Gosling, 1982;Wronski et al, 2013;Yom-Tov, 2016) but also as communication centres between individuals in the population (Johnson, 1973;Tučková et al, 2018;Wronski et al, 2013). Tučková et al (2018) showed that frequent visits to scent-marking stations improved bonds and group cohesion in different species of equids.…”

“…Scent-marking stations serve not only for male territorial marking (Gosling, 1982;Wronski et al, 2013;Yom-Tov, 2016) but also as communication centres between individuals in the population (Johnson, 1973;Tučková et al, 2018;Wronski et al, 2013). Tučková et al (2018) showed that frequent visits to scent-marking stations improved bonds and group cohesion in different species of equids. Sociality in females is linked to reproduction success (Cameron et al, 2009;Silk et al, 2003), reduces aggression and stress (Stanley & Dunbar, 2013) and thus increases fitness.…”