Mandrill (Mandrillus sphinx)

MORPHOLOGY: The average body mass for an adult male mandrill is between 21 and 28 kilograms, and for the female it is between 11 and 12 kilograms (Hill, 1970). The mandrill has a dental formula of 2:1:2:3 on both the upper and lower jaws (Ankel-Simons, 2000). The incisors of this species are broad and high-crowned (Caldecott et al., 1996). This species has pronounced maxillary ridges. The mandrill has a relatively short tail. The pelage color ranges from dark brown to charcoal-gray. The penis of the male is colored red and the scrotum has a lilac color. The face also has bright coloration like the genitalia and this develops in only the dominant male of a multi-male group (Dixson et al., 1993; Wickings and Dixson, 1992). Females and juveniles have a duller blue snout and a buffy colored beard (Rowe, 1996). The dominant male also tends to have a relatively heavier rump, larger testes, and higher plasma testosterone levels (Dixson et al., 1993; Wickings and Dixson, 1992). RANGE: The mandrill is found in the countries of Cameroon, Congo, Equatorial Guinea, and Gabon. This species is found in dense primary rainforest and sometimes secondary rainforest, gallery forest and coastal forest (Harrison, 1988; Rowe, 1996). Mandrills also can be found on plantations, examples being cassava, Manihot utilissima, and banana, Musa paradisiaca (Sabater Pi, 1972). Mandrills were found to be found in plantations during the dry season (Sabater Pi, 1972).

ECOLOGY: The mandrill is a frugivorous species, but also eats leaves, seeds, nuts, shoots, arthropods, crabs, fish, small vertebrates, and cultivated crops like manioc and oil-palm fruits. Tutin et al. (1997) found that in Lope Reserve, Gabon, the diet of the mandrill was composed of 50.7% fruits, 26% seeds, 8.2% leaves, 6.8% pith, 2.7% flowers, 4.1% animals, and 1.4% other. In Lope Reserve, Gabon, this species was found to avoid unripe fruit, even those of preferred food trees (Rogers, 1996). In captivity, individuals have been known to catch and eat house sparrows, Passer domesticus, that happen to fly in the cage (Mellen et al., 1981). The mandrill has also been observed hunting a young bay duiker, Cephalophus dorsalis (Kudo and Mitani, 1985). In Lope Reserve, mandrills will forage more in gallery forests and savanna-forest edge during the dry season (Rogers, 1996). This foraging strategy might be because in gallery forests and savanna-forest edge, fruit resources might be available were in the continuous forest they may be depleted (Rogers, 1996). This species mainly forages on the forest floor, but can feed in any level of the canopy (Estes, 1991; Hoshino, 1985; Harrison, 1988).

In Cameroon the diet of the mandrill was found to be composed of 84% fruit, 6% leaves, 7.6% animals, 1% mushrooms, 1% soils, and 0.3% other (Hoshino, 1985). Seeds were found to be the most important part of the fruit consumed, with seeds being the most consumed during the minor fruiting season (April-July) (Hoshino, 1985). During September to October fruits of the species Sacoglottis gabonensis were the most important fruit item consumed (Hoshino, 1985). During March fruit of the species Grewia coriacea were the most important fruit item consumed (Hoshino, 1985). Most leaves consumed were found to be herbaceous plants (Hoshino, 1985). Leaf items include: monocotyledonous plants, grass blades, and broad leaves (Hoshino, 1985). Animal food was mainly invertebrates such as ants, termites (Macrotermes mulleri), crickets, spiders, snails, and scorpions (Pandinus imperator) (Hoshino, 1985). The down birds and fragments of egg shells have been found in the feces of the mandrill in Cameroon suggesting that animals here consume birds and their eggs (Hoshino, 1985). Leaves were consumed more from April to July during the minor fruiting season (Hoshino, 1985). Animal matter, especially termites, are eaten more in two periods from April to June and from October to December (Hoshino, 1985).

In Gabon 75% of food eaten came from the ground and 25% from the trees (Norris, 1988). From the ground most of the food consumed was seeds or insects taken from the leaf litter (Norris, 1988). Plant parts eaten from the ground include: seeds, roots, fruits, leaves, stem pith, and the apical ends of branches (Norris, 1988). Plant parts eaten from trees include: mature and immature leaves, fruit, nuts, buds, blossoms, seeds, apical ends, stem pith, and bark (Norris, 1988). Younger mandrills were found to consume clay nodules, 2-5 centimeters in size (Norris, 1988). When foraging on the ground this species would forage in groups (Norris, 1988). Mandrills will forage in small ponds by standing at the edge and pull dead leaves from the bottom filtering out seeds and fruit (Norris, 1988). Most eating of food items occurred on the ground (77%) (Norris, 1988). In Gabon this species was found to have a feeding peak at about mid-day (Norris, 1988). Norris (1988) found that in Gabon males had a greater dietary diversity than females, but females spent more time feeding than males.

In another study in Gabon it was found that the diet of the mandrill included: fruits, leaves, bark, stems, fiber, fungi, and seeds (Lahm, 1986). Ripe fruits were preferred to unripe fruits, although unripe fruits may be consumed during the beginning of the fruiting season (Lahm, 1986). Cultivated plants consumed by this species include: palm nuts, manioc, bananas, mangos, pineapples, papayas, and avocados (Lahm, 1986, 1985). Cultivated plants are mainly consumed during the dry season (Lahm, 1986). Fruits eaten during this study were generally small to medium sized (Lahm, 1986). Vertebrate prey was found to be taken opportunistically, with terrestrial crabs and the African brush-tailed porcupine, Atherurus africanus, being an example of prey taken (Lahm, 1986, 1985). Beetles, ants, and spiders were the most frequent invertebrate prey consumed (Lahm, 1986). Beetles eaten were members of the family Scarabeidae, which are dung feeders (Lahm, 1986). The most consumed ant species include those members of the genera Odontomachus and Polyrachis (Lahm, 1986). Most foraging in this study occurred in primary forest (71%), with secondary and forest edge (14%) and riparian and inundated forests (14%) also important (Lahm, 1986, 1985).

Group sizes range from 15 to 95 members (Hoshino et al., 1984). At Lope Reserve, Gabon, the mean group size was found to be 150 individuals (Tutin et al., 1997). The mandrill is a terrestrial and diurnal species. Adult males are primarily found on the forest floor with adult females and juveniles found in the undergrowth and middle layers of the forest (Jouventin, 1975; cited in Mellen et al., 1981). This species has a relatively large home range as compared to other tropical forest primate species and this may be due to that mandrills primarily feed on fallen fruits on the forest floor (Hoshino et al., 1984). After the group leaves the sleeping site, they are moving constantly until dusk when they find a site and sleep for the night, sleeping in a different site every night (Hoshino, 1985). Group members do not all sleep in the same tree during the night (Norris, 1988). This species does not have the long rest period during the day typical of other primate species (Hoshino, 1985). Foraging has a peak during the early morning, and then decreases slightly staying at a stable level throughout the day (Hoshino, 1985). Food distribution influences the ranging patterns in this species (Hoshino, 1985). Mandrills spend more than half of their time (64%) feeding (Norris, 1988).

Predators of the mandrill include leopards, Panthera pardus, crowned hawk-eagles, Stephanoetus coronatus, potentially chimpanzees, Pan troglodytes, snakes, Bitis and Python, and humans, Homo sapiens (Mellen et al., 1981; Rogers et al., 1996; Harrison, 1988).

LOCOMOTION:
The mandrill moves through the forest floor quadrupedally (Fleagle, 1988). When walking this species tends to move slowly on the forest floor (Sabater Pi, 1972). The mandrill also moves slowly in the trees by clinging to lianas and small trees (Sabater Pi, 1972). This species will also climb into the trees and hide in the foliage when chased (Sabater Pi, 1972). This species will also make lateral jumps from tree to tree, which occur at heights of 2 to 5 meters from the ground (Sabater Pi, 1972).

SOCIAL BEHAVIOR: The mandrill has a unimalesocial system, with the leader male receiving most of the copulations. These small groups come together with other groups to form troops of up to 250 individuals, but sometimes a group does not form a troop with other one-male groups (Hoshino et al., 1984). Rogers et al. (1996) found that in Lope Reserve, Gabon, the social system was multimale-multifemale. Hoshino et al. (1984) found that multi-male groups are found during the minor fruiting season and one-male groups are found during the major fruiting season. During the major fruiting season the fruiting trees are patchily distributed in the forest and it might be easier for mandrills to move in smaller groups (Hoshino et al., 1984). In multi-male groups there tends to be one or a few more dominant males, with a hierarchy existing amongst the males (Kudo, 1987; Wickings et al., 1993). Wickings et al. (1993) found that in multi-male groups mating may be restricted to dominant males, those that have the prominent coloration on the face and the genitalia. Multimale-multifemale groups may form because increased predation protection and increased foraging efficiency (Rogers, 1996). Solitary males also occur in this species (Hoshino et al., 1984; Sabater Pi, 1972). Groups are made up of adult males, subadult males, adult females, and juveniles, with immature members comprising more than 50% of the group population (Hoshino et al., 1984). Males disperse from their natal group (Hoshino et al., 1984; Harrison, 1988). Groups stay in close together during the day, maintaining cohesion by use of the two-phase grunt and the crow calls (Hoshino et al., 1984). Hoshino et al. (1984) suggests, "the integration of a group of mandrills may be maintained by the members of a group focusing attention on adult males." This is not a territorial species, with smaller groups coming together easily without antagonism to form larger groups (Hoshino et al., 1984). Adult males initiate movement of the group (Sabater Pi, 1972). The mandrill was found to form mixed-species associations with Cercopithecus cephus and Cercopithecus pogonias (Sabater Pi, 1972).

In captivity it was found that the majority of social play occurs between infant males (Mellen et al., 1981). Adult females would play with infants but not with each other (Mellen et al., 1981). Social play consists of gnaw wrestling, wrestling, or chasing another individual (Mellen et al., 1981).

VOCAL COMMUNICATION:
two-phase grunt: This is a low and groaning two syllable sound with the energy concentrated in a low frequency range (Kudo, 1987). This call is emitted continually and regularly (Kudo, 1987). This call is emitted by adult males (Hoshino et al., 1984). This is heard when there is a change in direction of the group or at the start and end of travel (Hoshino et al., 1984). The function of this call is to guide group members during progressions (Kudo, 1987). This may be emitted in response to the crow call (Hoshino et al., 1984). This is the most frequent heard call by this species (Kudo, 1987).

roar: This call is made up of one syllable and is a low and groaning sound with energy being concentrated in a low frequency range (Kudo, 1987). This call may sound like the two-phase grunt call (Kudo, 1987). This call is either emitted as a single unit or in a repetition of 2-3 units (Kudo, 1987). Adult males are the only members of the group to utter this call and they emit it during group movement (Kudo, 1987).

crow: This call begins with a vibration followed by a continuous sound that has a harmonic structure (Kudo, 1987). This call is emitted by adult females and by juveniles (Hoshino et al., 1984). This is heard when individuals are found at the periphery of the group and there is a change in movement or direction of travel (Hoshino et al., 1984). This call occurs at the sleeping site, before and after beginning of group movement or crossing a river, changes of a direction of movement, and rejoining of groups (Kudo, 1987). This call functions "to coordinate the aggregation of animals as they formed subgroups and when the subgroups themselves aggregated" (Kudo, 1987).

yak: This call is a repetition of a sharp pulse-like sound that sounds like "kakaka" (Kudo, 1987). The duration of the call is 0.5-3 seconds (Kudo, 1987). All members of the group except for the adult male emit this call (Kudo, 1987). This call is heard when an adult male is emitting two-phase grunt and during the avoidance of an approach by an adult male (Kudo, 1987).

grunt: This call is a short and intense expiration of breath that is repeated once or twice (Kudo, 1987). This call is emitted by all members of the group and serves as a threatening call (Kudo, 1987).

growl: This call is a sequence of mild and rapid grunts or pants (Kudo, 1987). The sounds are separated by an interval of 0.07-0.18 seconds and the call occurs for 0.8-20 seconds (Kudo, 1987). The energy of this call is concentrated in the 0.05-0.95 kilohertz range (Kudo, 1987). This call is emitted by all members of the group (Kudo, 1987). This call is heard in mild alarm situations (Kudo, 1987).

K-alarm: This call is a two syllable call that is sharp and short (Kudo, 1987). This call is emitted in one unit with the second syllable louder than the first (Kudo, 1987). This call is uttered by all members of the group and is heard in situations of intense alarm (Kudo, 1987). Individuals will respond to this call by crouching and moving away (Kudo, 1987).

scream: This is described as a noisy sound that may resemble "gyaa" or "gii" (Kudo, 1987). This call occurs from 0.25 to several seconds (Kudo, 1987). This call is uttered by all members of the group (Kudo, 1987). This is heard in situations of escape/fear (Kudo, 1987).

girney: This call is a moaning and purring sound that sounds like "gyu-ruru" (Kudo, 1987). There is a short interval between durations of this call that can persist from 0.3-0.7 seconds (Kudo, 1987). The energy for this call is concentrated in the 0.8-1.2 kilohertz range (Kudo, 1987). This call is emitted by infants, juveniles, and adult females (Kudo, 1987). This call is heard during situations of appeasement by subordinates and during frustration by juveniles (Kudo, 1987). This is heard when individuals are attacked (Kudo, 1987).

grind: This call sounds like grinding of teeth (Kudo, 1987). This call is emitted by all members of the group (Kudo, 1987). This call is heard in tense situations (Kudo, 1987).

OLFACTORY COMMUNICATION:
sternal gland marking: This is when an individual will rub the sternal area against a substrate (Mellen et al., 1981). The chin is usually raised when performing this behavior (Mellen et al., 1981). This behavior is performed by all members of the group except for infants under 7 months of age (Feistner, 1991). In semi-free individuals, usually a vertical support was marked (Feistner, 1991). In a semi-free environment, individuals will mark repeatedly on certain supports (Feistner, 1991). Dominant males and females will perform this behavior more frequently than subordinates (Feistner, 1991). Mandrills will mark their sleeping sites (Feistner, 1991). This behavior is sometimes associated with tension after a disturbance (Feistner, 1991). This behavior may also facilitate orientation within the home range (Feistner, 1991).

VISUAL COMMUNICATION:
tension yawning: This is done by an adult male mandrill (Estes, 1991). This is when the mouth is opened fully to reveal the canines (Estes, 1991). This is done when a rival group or a predator is approaching (Estes, 1991). This display lasts from 4-5 seconds (Baenninger, 1987).

threat jerk: This display is a threat display. The head is jerked forward, while the eyelids are retracted, the medial crest is raised, and the lips are compressed forward. This is done sitting or standing. The ground may be slapped when performing this display (Mellen et al., 1981).

threat rush: This is when an individual will move rapidly and quadrupedally towards another individual, but not touching that individual (Mellen et al., 1981). This display serves to threat another individual (Mellen et al., 1981).

silent bared-teeth face: This is when in an individual the mouth is closed and corners of the mouth are drawn back to show the canines and premolars (Mellen et al., 1981). The lips are drawn together over the incisors to form a figure-eight (Mellen et al., 1981). The crest on the head is raised, the ears are flattened, and the head is shaken from side-to-side (Mellen et al., 1981). This display occurs in adult males, adult females, and infants, but in adult females and infants the lips do not make a figure-eight shape (Mellen et al., 1981). Infants will perform this display during and before play bouts (Mellen et al., 1981).

grooming solicitation posture: This is when an individual will stand quadrupedally with all four limbs fully extended and the tail flattened back over spine (Mellen et al., 1981). The head of the individual is held slightly up, oriented away from the potential groomer (Mellen et al., 1981). The hindquarters are pointed towards the potential groomer (Mellen et al., 1981). Another posture is when an individual is in a sitting posture with the neck or armpit oriented towards a potential groomer, with having little or no eye contact (Mellen et al., 1981).

presenting: This is when an individual will stand with limbs bent or crouched having the ventral (belly) area touching the substrate (Mellen et al., 1981). The perineum of the individual is oriented towards the receiver of this behavior (Mellen et al., 1981). The individual performing this behavior will continually look over their shoulder at the receiver of this behavior (Mellen et al., 1981). This behavior serves to solicit mounting from the receiver.

TACTILE COMMUNICATION:
social grooming: This is when one individual picks through the fur of another conspecific using the fingers, tongue, and/or lips (Mellen et al., 1981). Adult males tend to groom anoestrus adult females more than other males (Feistner, 1990). Adult females tend to groom other adult females than adult males, but during estrus adult females will spend more time with and groom adult males more than adult females (Feistner, 1990).

mounting: This behavior occurs from the dorso-ventral position (Mellen et al., 1981). The individual performing this behavior will grasp the receiver at the pelvic region with the hands (Mellen et al., 1981). The mounting individual will stand with the feet on the substrate (Mellen et al., 1981). The individual performing this behavior will thrust with the pelvis towards the individual receiving this behavior with intromission occurring or not (Mellen et al., 1981). In captivity adult males were found to mount adult females and rarely infant males (Mellen et al., 1981). Adult females were found to mount other infants than their own in captivity (Mellen et al., 1981).

REPRODUCTION: The mandrill gives birth to a single offspring. During estrus the perineum of the female swells and turns red. Estrus synchrony amongst the females in a group has been found in a semi-free population of this species (Feistner, 1990). In semifree-ranging individuals the birth season was from July to October (Feistner et al., 1992). The mean interbirth interval for the mandrill is 17.3 months (Feistner et al., 1992). Dominant males will guard females when the females are in estrus (Dixson et al., 1993). Sometimes an adult female will avoid or flee an adult male that is attempting to guard them (Dixson et al., 1993). Dixson et al. (1993) found that in a semi-free ranging group that the heavy rumped males fathered all of the infants and the solitary/periphery males did not father any. In captivity, mandrills can reproduce before reaching adult weight and dental complement (Feistner et al., 1992).

Mating occurs as follows: A male will walk after a female in estrus, with the female steadily walking and looking back at the male with her tail over her back (Mellen et al., 1981). During this a male will perform silent bared-teeth face and vocalize softly (Mellen et al., 1981). Then the female will present to the male, with the male performing mounting after (Mellen et al., 1981). The female may walk away, present, and the male may mount again (Mellen et al., 1981). During mounting thrusts, the female will look over her shoulder at the male (Mellen et al., 1981). After copulating, the female will run away and both individuals will finger their genitals and sniff and lick their fingers (Mellen et al., 1981). Copulations tend to occur during maximal swelling of the female (Feistner, 1990).

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