Erythrocebus patas

The patas monkey (Erythrocebus patas), also known as the wadi monkey or hussar monkey, is a ground-dwelling monkey distributed over semi-arid areas of West Africa, and into East Africa. It was formerly considered the only member of the genus Erythrocebus, but the Blue Nile patas monkey, previously synonymized with this species, was resurrected in 2018. There is some confusion surrounding the number of valid subspecies, with some listing four, and others listing two; the western Erythrocebus patas patas (Common patas; with a black nose) and the eastern Erythrocebus patas pyrrhonotus (Nisnas; with a white nose). Others, however, have suggested that at least some of the features used to separate these subspecies are merely variations in the female's facial pattern during pregnancy. On the other hand, the change in the nose during pregnancy occurs only in the West African populations. The male patas monkey grows to 60 cm (24 in) to 87 cm (34 in) in length, excluding the tail, which measures 75 cm (30 in). Adult males are considerably larger than adult females, which average 49 cm (19 in) in length. Adult males average 12.4 kg (27.3 lb) and adult females 6.5 kg (14.3 lb), showing a high degree of sexual dimorphism.Reaching speeds of 55 km/h (34 mph), it is the fastest runner among the primates. The life span in the wild can be up to about 20 years. It is found in many parts of central, western, and eastern Africa. It also has been introduced to Puerto Rico. The species avoids dense woodlands and lives in more open tropical savanna. The patas monkey lives in multi-female groups of up to 60 individuals (although much larger aggregations have been reported). The group contains just one adult male for most of the year. During the breeding season, there are multi-male influxes into the group. Once juvenile males reach sexual maturity (around the age of four years) they leave the group, usually joining all-male groups. The adult females in the group initiate movement of the group with the male following their lead. Variation in the female social structure of patas monkeys has been observed across different populations. This variation may be dependent on food resources, as conflict between individuals is often a result of competition for limited resources. Higher rates of conflict over dense, but limited, food, such as fruit bushes, is associated with more stable, well defined dominance hierarchies than habitats with more diffuse resources, such as insects. Variation in the availability of these resources has been associated with variation in dominance hierarchies among females. Conflict among females has also shown the presence of recognition among matrilineal relatives. It has been observed that, shortly after conflicts among two females, patas monkeys often act differently toward each other than if they had not been in conflict. Females often “reconcile” with each other by activities such as sitting together and grooming. While this reconciliatory behavior is observed even between unrelated individuals, it is most common among matrilineal relatives. Dominance structure has relatively little effect on the probability of reconciliation occurring, except that the alpha-female is the least reconciliatory of the females. Affiliation toward matrilineal relatives is common in other primates as well, such as vervet monkeys.