Erythrocebus patas is a medium sized, distinctive, terrestrial primate, native to sub-saharan Africa. Sexual dimorphism is conspicuous with adult males measuring up to 87cm tall and weighing between 10 and 12.5kg on average; adult females are much smaller, averaging 49cm tall, and around 5-6 to 6.5kg in weight (Nakagawa, 2003; Fedigan, 1992). Adult males also have much larger canines than females and are sometimes described as being brighter in colour (Fedigan, 1992). The fur of the dorsum, cap, neck and tail are reddish-brown. The ventrum and limbs are grey-white in females and bright white in males. Face black, with white, grey or black nose. Cheeks white or grey. Males exhibit a bright blue scrotum. Hands and feet are prehensile with opposed thumbs. E. patas is adapted for life in open country, having slender bodies and long limbs suited for ground speed rather than arboreal movement. They are the fastest primate on land and may reach speeds of 55 km/h (Hall, 1965). Although quadrupedal, they assume a bipedal stance when alarmed.\r\n

E. patas occur in single-male, multi-female groups for most part of the year. Group size varies widely between 5 – 74 (Chism & Rowell, 1988). Extragroup males live solitary or in all-male groups (Harding & Olson, 1986). Multi-male influxes into heterosexual groups occur during the mating season (Hall, 1965; Harding & Olson, 1986; Struhsaker & Gartlan, 1970). Shy behaviour, low densities, cryptic pelage, and large home ranges makes it hard to observe them in many parts of their natural range (De Jong et al., 2008). In the past, patas monkeys rarely came into conflict with humans, but the growing human population (in Kenya for example) has forced farmers to exploit dryer areas, converting patas habitat into agricultural land (Isbell & Chism, 2007; De Jong et al., 2008). E. patas frequently invades farms, consume produce and are considered pests in some parts of their geographical range, mainly in west Africa. Once this primate looses its fear for humans it can act aggresively towards them when treatened. This can be potentially dangeruous due to disease transmission between primates and humans.

There are four proposed subspecies of Erythrocebus patas according to Hill (1966) and Kingdon (1997) (E. p. patas, E. p. pyrrhonotus, E. p. baumstarki, and E. p. villiersi), opposed to Isbell (in press), who recognises three subspecies (E. p. patas, E. p. pyrrhonotus, E. p. baumstarki), Dorst and Dandelot (1969), who recognised two subspecies (E. p. patas, E. p. pyrrhonotus) or none by Groves (2001, 2005) and Grubb et al. (2003).\r\n
E. p. patas occurs from Senegal to Chad, E. p. pyrrhonotus occurs from western Ethiopia to northern Uganda and west, northwest, central and south of Kenya (De Jong et al., 2008), E. p. baumstarki is restricted to central north Tanzania (De Jong et al., 2008; De Jong et al., 2009) and E.p. villiersi is restricted to the Aïr Massif in Niger (Dekeyser, 1950).

Erythrocebus patas have a birth interval of ca. 1 year. At birth, infants are black and a reddish coat emerges after about three months. For the first four to five months infants receive much attention and grooming. Infants are fully capable of feeding and transporting themselves by 12 months of age (Chism et al., 1984). Complete weaning only occurs when a new infant is born, usually at age one. Allomaternal caretaking by females promotes infant survival (Chism et al., 1984).

Patas monkeys are used as laboratory animals primarily for biomedical and behavioral research (González-Martínez, 1998).

Erythrocebus patas inhabits savannah, woodland savannah and grass steppe with thicket clumps. They generally avoid dense vegetation like riverine vegetation and forests. E. patas travel long distances using the ground. When disturbed they will either flee using the ground or move into tall trees for safety. For their sleeping sites they require an area with tall trees. E. patas needs to drink daily (Struhsaker & Gartlan, 1970; Chism & Rowell, 1988; De Jong et al., 2008). In dry areas, or during the dry season, E. patas does not move far from permanent water sources (which can be man-made water sources; Enstam & Isbell, 2004; Isbell & Chism, 2007; De Jong et al., 2008). In their natural habitats, groups have large home ranges varying typically between 23-52 km², depending on their group size, food and water availability (Chism & Rowell, 1988; Enstam & Isbell, 2004; Hall, 1965).\r\n\r\n

The introduced population of E. patas in Puerto Rico occupies substantially smaller home ranges, varying from 3.72 km² to 15.39 km² (González-Martínez, 1998). González-Martínez (1998) suggests that ‘the resource availability of Puerto Rico is adequate to sustain high densities in a small home range while maintaining a group size structure similar to that found in the natural habitats.’ The Puerto Rican population exhibit territorial behavior, with groups having well established boundaries. Populations occurring in their natural habitats have typically large, highly overlapping home ranges (González-Martínez, 1998).

Sexual, polygenous groups, typically including a variable number of females and one male (Chism & Rowell, 1988; Hall, 1965). Females reach sexual maturity at 2.5-3 years and males reach sexual maturity at 4-4.5 years (Chism et al., 1984). Males leave their natal group around puberty (ca. 3 years; Hall, 1965, Chism et al., 1984, Nakagawa et al., 2003). All-male groups occur. Multi-male influxes into heterosexual groups occur during the mating season (Hall, 1965; Harding & Olson, 1986; Struhsaker & Gartlan, 1970). Males are promiscuous and can fertilize many females in a short period of time. Females need to be in their estrous cycle to be fertile and receptive to males. Their defined reproductive season takes place during the wet summer. Strong correlative findings indicate breeding is largely based on rainfall. After a gestation period that lasts ca. 170 days, females give birth to a single baby, usually every year (González-Martínez, 2004; Gron, 2006).

Erythrocebus patas are omnivorous primates. Their diet varies with changes in food availability due to the seasonality of its environment. E. patas primarily feeds on plant material (flowers, fruits, gum, seeds and leaves), insects, and animal material (vertebrates, birds’ eggs and nestlings; Isbell, 1998). They catch and eat lizards and fish. In Kenya and Tanzania E. patas are strongly associated with Acacia woodland (Chism & Rowell, 1988; Isbell, 1998; De Jong et al., 2008; De Jong et al., 2009; Isbell in press). The diet of a population studied on the Laikipia Plateau in Kenya was found to be highly dependent on Acacia drepanolobium (feeding on the gum and ants that occupy the swollen thorns of this tree; Isbell, 1998). \r\n\r\n

In Puerto Rico E. patas movement is correlated to the occurrence of their most important food sources: Tamarindus indica, Melicoccus bijugatus, Mangifera indica, Prosopis juliflora, Leucaena leucocephala, and Bourrerria succulent. E. patas feeds most often on fruits, seeds or the seed pods of these trees or shubs. Other items in their diet in Puerto Rico are arthropods and human crops taken from agricultural plots (González-Martínez, 2004; Felix Grana., pers.comm., November 2007).

E. patas is an internationally popular laboratory species, used for biomedical and behavioural research.

Erythrocebus patas (individuals originated from Nigeria) were intentionally released to the Islands of Cueva and Guayacan, in Puerto Rico between 1971 and 1981, by the La Parguera Primate Facility. Between 1974-1981 individuals have gradually migrated from the Islands to mainland Puerto Rico and formed free ranging population groups (González-Martínez, 1998). In 1993 the population size on the mainland of Puerto Rico was estimated to be 120 individuals (González-Martínez, 1998). In 2006 the estimated population size was between 514 to 621 individuals (Massanet & Chism, 2008). The rapid expansion of the E. patas population in Puerto Rico is due to factors such as lack of non-human predators and abundant resources according to Massanet and Chism (2008).

In Puerto Rico, E. patas is considered a pest on various levels. They frequently invade fruit farms and raid crops. Their size, strength, and lack of fear for humans renders them a potential threat to humans and domestic animals. They may carry diseases that can be passed on to humans. Additionally, they are voracious omnivores and may have an impact on populations of native plants and small animals (Felix Grana., pers.comm., November 2007). There is not enough information about their role as predators on the local avifauna but it is likely that bird species in the Sierra, including the 'Critically Endangered (CR)' Puerto Rican nightjar (see Caprimulgus noctitherus in IUCN Red List of Threatened Species) and the 'Endangered (EN)' yellow-shouldered blackbird (see Agelaius xanthomus in IUCN Red List of Threatened Species), could suffer from nest predation by exotic species such as E. patas (Aukema et al., 2006).

Preventative measures: Restrictions on the importation of Erythrocebus patas, as well as suitable enclosures, can prevent their establishment in new locations. Trade and sale of all primates is restricted in Puerto Rico (Felix Grana., pers.comm., November 2007).\r\n

Physical: An effort to find an efficient way of eradicating wild populations of patas monkeys in Puerto Rico is underway (Felix Grana., pers.comm., November 2007).