The patas monkey, 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.
The male patas monkey grows to 60 cm to 87 cm in length, excluding the tail, which measures 75. Adult males are considerably larger than adult females, which average 49 cm in length. Adult males average 12.4 kg and adult females 6.5 kg, showing a high degree of sexual dimorphism. Reaching speeds of 55 km/h, it is the fastest runner among the primates.
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.
Patas monkeys have several distinct alarm calls that warn members in the group of predators. Different alarm calls are given by different group members and certain alarm calls are distinctive of different types of predators. Unlike other primates, patas monkeys rarely take refuge from predators in trees. This is most likely the due to the relatively sparse tree cover in patas monkey habitats. While patas monkeys usually run on the ground away from predators, individuals have been observed to attack predators such as jackals and wildcats. This behavior has been observed in both males and females.
Source : wikipedia