Ecology, Behaviour and Threats of Patas Monkey (Erythrocebus Patas, Schreber, 1775): a Review Paper

Ecology, behaviour and threats of Patas monkey (Erythrocebus patas, Schreber, 1775): A Review paper

Israel Petros Menbere*

Department of Ecotourism and Biodiversity Conservation, Madawalabu University, P.O.Box-247, Tel: +251- 93-9170073, Bale Robe, Ethiopia, Email: [email protected]

* Corresponding author, [email protected]

ABSTRACT

The Patas Monkey (Erythrocebus patas), is a ground-dwelling medium sized primate distributed from West to Eastern Africa. It is the only species of the genus Erythrocebus. Patas monkeys exhibit an apparent feature of sexual dimorphism. Adaptation to a wide range of ecological conditions is also common, despite preference has been demonstrated to open habitats. Savannah grassland, shrub lands and acacia woodlands are their major habitats. Over 65% of Patas monkeys foraging activity is carried out on the ground. Grasshoppers, insect larvae, winged ants, leaves, flowers and fruits are main diets of Patas monkeys. They spend most of their daily time for travelling and feeding. They live in multi-female social groups of 20 to over 75 individuals. The groups contain one adult male for most of the time and only the females are permanent members. Polygynous and all-male groups are the two distinct types of their social organizations. Their reproduction is characterized by a defined conception and birth season. Signs such as body postures and facial expressions play a significant role in their communication. They also make low intensity calls for communication. Habitat degradation, fragmentation and loss are the major threats affecting Patas monkeys in their natural range.

Key words: Patas monkey, ecology, behaviour, reproduction, threats

INTRODUCTION determine two subspecies, the western E. p. patas and the eastern E. p. pyrrhonotus. Others, however, The Patas monkey (Erythrocebus patas) is one of the believe that at least some of the features used to medium-sized primates distributed from semi-arid separate these subspecies are merely variations in areas of West to Eastern Africa. It is recognized by its the female's facial pattern during pregnancy (Groves, different names like Red or Hussard monkey given 2005). due to its red-brown and silver-grey morphological colour. It is also named as crying monkey after the Patas monkeys are one of few primates having weeping sounds of its young (Galat-Luong, 1992). physical adaption for life on the ground (Schmidt, Patas monkey is a semi-terrestrial primate typically 2010). Their slender bodies and long limb structures living in multi-female or single-male social groups made their terrestrial movement and speed more composed of 75 individuals (De Jong et al., 2009). suitable (Gartlan, 1974). The locomotion of Patas monkey is very swift among primates, reaching a Patas monkey is the only species classified under the maximum speed of 55 km per hour (Hall, 1965). They genus Erythrocebus. However, there are four are fast runners and quit terrestrial primate (Hall, proposed subspecies such as, E.p. baumstarki, 1968; Yirga et al., 2010). This high speed running of E.p.patas, E.p.pyrrhonotus and E.p.villiersi. These Patas has a functional support to escape from subspecies are dubious. As a result, there is some predators (Etter, 1973). The life, locomotion and bewilderment in determining the number of valid resource use of Patas monkey in savanna habitats subspecies. According to Kingdon (1997) four make them distinct among African monkeys (Zihlman subspecies listed while Dorst and Dandelot (1969) and Underwood, 2013). Am. J. Sci. Ind. Res., 2016, 7(3):60-68

Patas monkeys (Erythrocebus patas) as one of the METHODS most terrestrial monkeys, they have a very large home range (Schmidt, 2010). They occupy arid This paper was based on studies carried out on environments where resources are insufficiently Patas monkeys over the last 40 years. Relevant existing (Milton and May, 1976). The adaptability of literatures were also reviewed on their ecology, Patas monkeys in habitats characterized by arid behaviour and threats. Although not all sources were environmental condition in Kenya contributed for their included, adequate amount was explored. This safe existence. This is due to the places are not used review paper followed a descriptive approach based for agricultural activity which is the main threat of on scientific findings from different sources. Patas monkeys (Isbell and Chism, 2007). However, Moreover, recent articles related with Patas monkeys combination of habitats that involve grassland and are also assessed from different internationally woodland vegetation structures are the preferred published journals for better description about the ecosystems by Patas monkey (Henty and McGrew, species. 2014). Morphology: Patas monkeys display a large degree Patas monkey is an omnivorous primate, relying on of sexual dimorphism (Loy, 1989). The average plant material, insects, and animal material for weight of adult male is 12.4 kg whereas adult female sustenance. The majority of their feeding activity weights 6.5 kg (Galat-Luong et al., 1996). The body takes place on the ground (Isbell, 1998; Henty and length of Patas male ranges from 600 to 875 mm McGrew, 2014). They also invade farms, consume excluding the tail, and the female measures 490 mm farm products and hence act as pests (Chism and on average (Rowe, 1996). Adult male Patas has Rowell, 1988). brighter colour and bigger size than adult females. Moreover, males possess white beard, gray forelimb The ecology and behavior of Patas monkey has been and chest and bright blue scrotum whereas females studied in different countries in the world. Patas have a tan coloured dorsal part (Yirga et al., 2010; monkey exhibits ecological and behavioral Rowe, 1996). Features such as black face with white characteristics more similar to other primates. moustache, reddish-brown head crown, brownish- However, it appears to be unique in some of its white neck, black line/strip on temporal suture/lines physical and social adaptations to a terrestrial mode and whitish ventral parts are common to both sexes of life. Moreover, there is also an ever increasing of Patas monkeys (Yirga et al., 2010). The maximum threat of Patas in different parts of its natural range. recorded longevity of a Patas monkey in the wild is Hence, the main objective of this paper is to review 21.6 years (Ross, 1991). The morphology of Patas the ecology, behavior and threats of Patas monkey monkey is indicated in (Fig. 1). associated with its physical and social attribute.

Fig.1. Back and front views of adult male Patas monkey (Erythrocebus patas pyrrhonotus) in Anbesa Chaka, Bambesi Woreda of Benishangul-Gumuz Region, Western Ethiopia (Yirga, et al., 2010).

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Geographic distribution: Patas monkeys dwell in al., 2008). They also make use of human made the geographic range of south of the Sahara Desert resources like water, crops and places with reduced and north of the tropical forest belt. They are found in predators in some occasions (De Jong et al., 2008). habitats characterized by grasslands and woodland- Patas were demonstrated to prefer grassland in the savannahs from Senegal to Ethiopia. In East Africa, wet season and sleep in woodlands to avoid they exist in Uganda, Kenya, Tanzania and Sudan predators (Nakagawa, 1999). When offered a choice (Isbell and Chism, 2007), whereas in west Africa, between short and tall trees, Patas prefer tall trees they are found in Mauritania, Mali, Niger, Cameroon, (Enstam and Isbell, 2004). Togo, Côte d'Ivoire, Ghana and Nigeria (Rowe, 1996). Other countries that make up the Patas Foraging behavior: Patas undertake over 65% of monkey range include Benin, Burkina Faso, Gambia, foraging activity on the ground. Their diet is Guinea, Sierra Leone, Congo, the Central African composed of grasshoppers, insect larvae, a mantis, Republic and Chad. weevils, winged ants, leaves, buds, flowers and fruits (Henty and McGrew, 2014; Raubenheimer and Ecology: The Patas monkeys are diurnal primates. Rothman, 2013). They also act as nuisance species They habitually dwell in habitats where open areas prowling crops of local peoples in their range. This is are prevalent, despite their adaptation and tolerance particularly the case for all male groups of Patas to a wide variation of ecological condition including monkeys that infrequently raid crops in their those highly arid environments (Tappen, 1960). They surrounding farm lands (Yirga et al., 2010; Gonz occupy areas ranging from savannah to woodland, ález-Martinez, 2004). The Patas monkeys spend a and from extreme desert to relatively wetland habitats large amount of time searching for uncommon and (Hall, 1965; Chism et al., 1984). The home ranges of hardly obtained food items such as gums and Patas troops in their natural habitats also vary from arthropods (Isbell et al., 2012; Nakagawa, 2000). 23 to 52 km², depending on their troop size, food and These food items are important in meeting the water availability (Chism and Rowell, 1988; Enstam nutritional requirements of the monkeys. Due to the and Isbell, 2004). high reliance on gums and insects for their diet, Patas monkeys are by far the physically largest The occurrence of Patas monkeys in open habitats primarily insectivorous and gummivorous primate such as savannah grassland, shrubland and Acacia (Isbell, 1998). As shown in (Fig. 2), in Kenya, they woodland is associated with their physical adaptation are strongly associated with Acacia woodland for for running on the ground (Galat-Luong, 1992; De their diet where gums and arthropods are Jong et al., 2009). In dry areas or during the dry predominately available (Isbell, 1998; De Jong et al., season, E. patas does not move far from permanent 2008). water sources (Isbell and Chism, 2007; De Jong et

Fig. 2. Adult male Patas monkey Erythrocebus patas pyrrhonotus in Acacia drepanolobium woodland, Ol Pejeta Conservancy, Laikipia District, Kenya (De Jong et al., 2008).

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The distribution of food items in time and space affect only females are permanent members. Young males the feeding behaviour and group associations of leave their natal troop shortly before adolescence Patas monkeys. As a result, they travel more and females remain within the natal troop (Galat- distance between food sites, stay for short duration at Luong et al., 1994). Most young males leave their food sites and rapidly move to obtain their food. They natal troop at the age of 3 years, which is before depend on less abundant, highly dispersed and small reaching sexual maturity (Chism et al., 1984; sized food sources. This makes their locomotion Nakagawa et al., 2003). When they leave at sexual rapid in open habitats, and thereby assists to escape maturity, they may join an all male group or may live from predators (Isbell, et al., 1998). a solitary lifestyle until they win positions in troops with females. Behaviour: Patas habitat is marked by seasonality between dry and wet seasons, and behavior changes Unlike numerous other primate communities, Patas accordingly between these seasons in relation to females take a key role to lead their troop and protect their proximity and availability of water. During wet their home ranges from intrusion by other troops. season, less drinking behaviour is displayed whereas Adult males usually stay in their peripheral position at during the dry periods, they congregate around water the back. The males commonly observe the sources (Hall, 1965; Struhsaker and Gartlan, 1970). surrounding environment and when they notice threats they move to the leading position of the troop The Patas monkeys spend most of their daily time for (Yirga et al., 2010). The males play a role in travelling and feeding. Seasonal availability and defending the troop from predators and other troops distribution food resources are important for their whereas protecting the young members from danger behaviour (Schmidt, 2010). They are active in the is the females’ activity (Loy, 1989). morning and afternoon with some resting in the During breeding season, occasionally nonresident midday (Nakagawa, 1989). During the morning and males will enter the troop and mate (Cords, 1987), afternoon activity periods, time is spent feeding, but usually only the resident male is responsible for grooming, and on social activities, with grooming and copulation (Galat-Luong et al., 1994). The resident social activities mostly taking place in the morning male generally stays on the edge of the troop, and (Hall, 1965). During the night, the Patas rest on trees, only interacts with the females for breeding. Females on the edge of the grassland, prefer to sleep one will harass the resident male if he is nearby during individual per tree, except in the case of mothers with other seasons and this prevents male aggression infants, who will remain together (Chism et al., 1983; towards females (Loy, 1989; Chism et al., 1984). Fleagle, 1988). Patas males involve in group relationships that Their flighty behaviour, low population density and enhance their mating chances. This is signaled larger home ranges make observation of Patas during mating seasons, in which arrivals of many monkeys difficult in their natural habitat (De Jong et males occur (Cords, 1988). This phenomenon serves al., 2009; Schmidt, 2010). They also use different as a strategy to prevent infanticide as new resident predator escaping techniques such as running, males less likely engage due to the confusion related watchfulness and crypsis (Zihlman and Underwood, with paternity (VanSchaik, 1996). When aggressive 2013; Marshack and Pruetz, 2009; Enstam and new males invade the social system of Patas during Isbell, 2002). Potential predators of the Patas mating seasons, the resident male evicts the monkey include dogs, humans, felids, hyenas, invaders from the group (Enstram et al., 2002; raptors and possibly baboons (Chism and Rowell, Ohsawa, 2003). 1988; Enstam and Isbell, 2002). Chimpanzees also predate on Patas monkeys. But, Patas monkeys Females groom each other and let other adults and escape them by running on the ground rather than immature females take care of their infants (Chism et moving on the tree (Marshack and Pruetz, 2009). al., 1984). Whereas males spend a large part of their time scanning the landscape for predators, males Social behavior: The Patas monkey lives in multi- from other troops or each other so that they are female troop of 20 to over 75 individuals (Enstam et constantly aware of other individuals within the troop, al., 2002; Ohsawa, 2003). The troop contains just which may serve to reduce agnostic encounters one adult male for most of the year (Arsuaga and (Nakagawa, 1992; McNelis and Boatright, 1998). This Ignacio, 2006). In social groups of Patas monkeys, behavior serves several purposes. The scanning

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alerts the Patas in a troop to the presence of social organization due to one male is accompanied predators and to align them. It may also serve as a by several females and their young. There is a low social monitoring process and helps to maintain male to female proportion in Patas (Galat-Luong, coherence of troop members (Rowell and Olson, 1992). And, males are known to be crucial for 1983; Hall, 1965; Nakagawa, 1992). females particularly as protectors from external danger in Patas monkeys (Hemelrijk and Luteijn, Social organization: Two distinct types of group 1998). Patas monkeys are under dispersed, and organizations can be observed among Patas female synchrony is identified when a male influx monkeys over the majority of the year. The first type occurs. Patas males increase their reproductive is the polygynous group of variable number of opportunity be smitten by fertile females during females and one male. The other type is that of all- mating season (Nunn, 1999). male groups although occasionally mixed-sex groups with two adult males (Struthsaker and Gartlan, 1970; During the mating season, invading by solitary males Gartlan, 1974). The purpose of all-male Patas group results in the formation of multi-male and multi- appears to provide safety and protection for young female troops chasing the resident male. In males against predators and other threats (Ohsawa, occasions when females are not receptive, relatively 2003). It appears that all-male groups are typically stable groups with one adult resident male and smaller than the polygynous groups (Struhsaker and several females occur. At the end of the mating Gartlan, 1970; Ohsawa, 2003). season, one-male, multi-female troops stabilize (Ohsawa, 2003). Female social organization: In Patas monkeys, females have weaker, non-linear dominance Reproduction: Patas monkeys have a clearly hierarchies that are unstable for long periods of time defined conception and birth season (Henty and (Isbell and Pruetz, 1998). Even though such a weak McGrew, 2014). During estrus, the female will solicit or non-existent dominance hierarchy characterizes copulations from the male by crouching, then blowing Patas females, no emigration of females from their air into her cheek pouch, and then drools, with the tail natal groups occurs. Patas habitats possess not curled up (Hrdy and Whitten, 1987). Typically, clumped, and randomly distributed food resources conception occurs in the wet season and births occur and this would be the cause for their non-linear in the winter dry season (Nakagawa et al., 2003; dominance hierarchies. The spatial distribution of Chism et al., 1983). Evidences indicate that food resource is vital in determining dominance reproduction in Patas monkeys are related to rainfall interactions (Pruetz and Isbell, 2000). distribution. They also have gestation duration around 170 days, and in these occasions females The social structure of female Patas monkeys varies give birth to a single baby (González-Martínez, depending on the availability of resources as limited 2004). food resources can cause more competition between individuals of a species. The variation in social Patas monkeys demonstrate high population structure of Patas relates to the female social fluctuations. They have one of the shortest inter birth strategies, the ways in which females use social intervals of any Cercopithecine, averaging about one behaviour to attain their reproductive goals. Hence, year between births (Chism et al., 1984; Nakagawa competition for food sources is determinant in female et al., 2003). The infants also become fully social relationships (Sterck, et al. 1997). The independent by one year of age as they will be presence of conflict among female Patas monkeys displaced by new infants. The early and frequent has also been observed in the presence of reproduction of Patas has been associated with their recognition among matrilineal relatives. However, relatively lower survival of adults compared to shortly after conflicts among females, Patas monkeys immatures (Isbell et al., 2009). Their dependence on often reconcile by sitting together and grooming (York gums and arthropods for their diet have also a and Rowell, 1988). considerable significance to their frequent reproduction as the same reproductive outputs have Male social organization: The social organization of been observed in other gummivorous and male Patas monkeys varies with mating which is insectivorous primates (Isbell et al., 2012). seasonal and occurs during the wet season. The Patas monkey is characterized by having a uni-male

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There has also been at least one instance of resources is also affecting the population in the probable infanticide by a Patas male observed in the region. The influence of growing human population is wild (Enstam et al., 2002). However, infanticide is leading to anthropogenic impacts on Acacia beneficial when a male may only have a short time to woodland habitats on which Patas are dependent for mate before being supplanted by another male and their survival (De Jong et al., 2009). Intensification of when access to females is limited (Hrdy, 1974). farming activities and high production of charcoal are also threatening the habitats of Patas monkeys (Isbell Communication: Primates display a variety of social and Chism, 2007). systems and this makes their communication more complex (Saltzman, et al., 2010). Patas monkey rely Conclusion: The Patas Monkeys (Erythrocebus less on olfaction. This might be due to absence of patas), are among the semi-terrestrial African marked specialized glands and scent-marking primates. They dwell in variety of habitats including behaviours. Tactile communication and visual harsh environments. Patas do over 65% of their displays are the common mechanisms of feeding occurring on the ground. They feed on communication in Patas monkeys (Walker, 1998). insects, gum, fruits, flowers and others. They live in Particularly, communications through facial multi- female social groups of 75 individuals. In their expression are prevalent. Vocalizations are relatively social group, one adult male exists for most of the less recorded in Patas related with their silent time. Polygynous and all-male groups are their two behaviour. Moreover, the exhibition of a low distinct types of group organizations. Reproduction in frequency contact calls in Patas may be as a result of Patas is characterized by a clearly defined the open nature of their habitat, that leads to conception and birth season. Conception occurs in intensification of visual contact (Nakagawa, 1992). In the wet season while and births occur in the winter the communication of Patas monkeys, signs such as dry season. Patas monkeys mainly communicate body postures and facial expressions have a through visual contact. But, they also use alarm calls significant function (Yirga et al., 2010). to warn their members in the presence of predators. Patas monkeys are facing significant threats in their Alarm calls: The vocal communication of Patas natural range. Habit degradation, fragmentation and monkeys is vital in keeping members of their troop loss are their major conservation challenges. from danger such as predator threats. They are known to give alarm calls that differ in age and sex ACKNOWLEDGEMENTS categories. However, the vocal communication of Patas monkey is not mostly detected from a distance I would like to forward my gratitude to Prof. M. of less than 50 m for humans. This happens as they Balakrishinan for his constructive comments, don’t make calls in near contact with peoples and invaluable guidance and encouragement in the their low intensity call which is inaudible to individuals overall aspects of this review paper. I am greatly (Henty and McGrew, 2014). indebted to the Department of Zoological Sciences, Addis Ababa University for facilitating the review Patas monkeys have various alarm calls, which in work. many cases are predator specific; however, males only utter the "bark grunt" in response to all REFERENCES predators. This type of grunt is also vocalized by males in response to the approach of extra-group Arsuaga, J. L and Ignacio, M (2006). The chosen males (Enstam and Isbell, 2002). Unlike, adult male Species: the long march of human evolution. Patas monkeys, other social groups exhibit several London: Blackwell Publishing. discrete alarm calls which are used to warn the Chism, J and Rowell, T. E (1988). The natural history members of the troop during the presence of danger. of patas monkeys. In: Gautier HA, Bourlière F,

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