Vervet Monkeys: Aspects Of Their Ecology And Behaviour

The Vervet monkey (Chlorocebus pygerythrus) is an Old-World monkey of the family Cercopithecidae native to east Africa. They are semi-terrestrial and medium-sized monkeys with long tails; the average body length for an adult male is about 50 centimetres and about 40 centimetres for female adult. This species is widely spread in east Africa and their common habitat is Acacia woodland along watercourses (Kingdon et al., 2013). They are highly social animals living in troops consisting of a dominant male, several females and their offspring and a few adult males. The females never leave their troop unlike the males who are emigrating when they reach sexual maturity (Borgeaud et al. 2016). They are very territorial animals and have defined home range boundaries. Groups of vervet monkeys usually occupy relatively small territories and aggressively defend them from other groups intrusion. (Isbell, Cheney & Seyfarth, 1990)

Vervet monkeys are omnivorous and they are both arboreal- and terrestrial foragers. According to Kingdon et al. (2013), they prefer to feed in trees during the morning hours and descend to the ground by mid-morning. Important food includes seeds, flowers, foliage and gum. In some areas small vertebrates of insects are consumed (Kingdon, 2015). Vervet monkeys have cheek pouches and after they are filled with food they sit down, chew the stored food and swallow it (Gartlan, 1966).

It has been widely studied that the availability of food resources affetcs activities, breeding and behaviour patterns in several primates species, including Vervet monkeys (Hauser & Fairbanks, 1988). Indeed, for instance, in South Africa, the wet season lasts from October to March, which corresponds with the period when the reproductive rates are higher and the mortality lower. This can be explained by the increase of food availability due to the rain, and so the decrease of energy spent on foraging (Lee & Hauser, 1998). Even the temperature can influence general behaviours of the Vervet Monkeys. Some studies have pointed at that, during the non-mating season, heat is leading to a decrease of time spent feeding by the monkeys, while an increase of time spent resting is visible (McFarland et al., 2014). Also, when it gets colder, male vervets tend to sunbathe more, decreasing physical activity and they spend more time together with other males (Danzy et al., 2012)

Their time spent feeding varies seasonally. However, this does not vary within or among groups, or between habitats, males and females or dominants and subordinates. Nevertheless, males spend more time scanning for predators or other males wanting to join the group from the top of the trees. Hence, they spend more time alone and less time allogrooming than females. (Isbell & Young, 1993).

Even though some ethnological studies have been done on Vervet monkeys, most of the research about this species is biological or medical. Moreover, the few ethnological studies that exist about Vervet monkeys are mostly focused on their feeding ecology. Hence there is still a lot to find out about their general behaviours and social structure.

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