Social organization and space use of a wild mandrill (Mandrillus sphinx) group

Abstract

Mandrills (Mandrillus sphinx) are enigmatic Old World primates whose social organization and ecology remain poorly known. Previous studies indicated, for example, that groups are composed of only adult females and their young or that several units composed of one adult male and several females make up larger permanent social units. Here, we present the first data on group composition and male ranging patterns from the only habituated wild mandrill group and examine how home range size and daily path length varied with environmental and demographic factors over a 15-month period. Our study site is located in southern Gabon where we followed the group on a daily basis, collecting data on presence, ranging, behavior, and parasite load of its individual members. Throughout the study, the group was made up of about 120 individuals, including several non-natal and natal adult and sub-adult males. One-male units were never observed. The mandrills traveled an estimated 0.44-6.50 km/day in a home range area of 866.7 ha. Exploratory analyses revealed that precipitation, the number of adult males present, and the richness of protozoan parasites were all positively correlated with daily path length. These results clarify the social system of mandrills and provide first insights into the factors that shape their ranging patterns.

Environmental and individual determinants of parasite richness across seasons in a free‐ranging population of Mandrills (Mandrillus sphinx)

“…Indeed, the park's fences have never constituted a restraint on animal movements (see Fig. 3 in Brockmeyer et al, 2015). Moreover, other wild mandrill groups of unknown sizes are known to live in the park but we have never witnessed intergroup encounters.…”

“…Indeed, in captivity, individuals live year-round in the same restricted area of a few hectares, where contamination risks are high. In the studied population, mandrills travel on average 2.4 km/day (Brockmeyer et al, 2015) and tend not to stay in the same area for several consecutive days (MJEC, unpublished data). When they return to an area that has been visited earlier during the rainy season, rainfall may have cleared up the site.…”

“…In addition, fecal samples from identified animals are collected opportunistically. In 2014, the population comprised about 120 to 140 habituated individuals (for details on the population, see Brockmeyer et al, 2015). The mandrills occupy a home area of 866 ha that exceeds the park's boundaries, as they may spend weeks outside the park.…”

A Comparative Study of Four Methods for the Detection of Nematode Eggs and Large Protozoan Cysts in Mandrill Faecal Material

“…In 2003, wild males joined the group and females gave birth during the first postrelease year. In July 2015, the group was composed of a total of 125 individuals, including more than 85% of wild-born animals habituated to human presence [Brockmeyer et al, 2015]. Since early 2012, the group has been followed every day from 6 a.m. to 6 p.m. by field assistants [Brockmeyer et al, 2015].…”

“…In July 2015, the group was composed of a total of 125 individuals, including more than 85% of wild-born animals habituated to human presence [Brockmeyer et al, 2015]. Since early 2012, the group has been followed every day from 6 a.m. to 6 p.m. by field assistants [Brockmeyer et al, 2015]. During daily behavioural monitoring of the population, human observers collected fresh faecal samples.…”