Drill (mandrill)

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TAXONOMY

Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Cercopithecinae
Genus: Mandrillus
Species: M. leucophaeus, M. sphinx

Other names: M. leucophaeus: Papio leucophaeus, drill; drill (Danish, Dutch, French, German, Spanish, Swedish); Drilli (Finnish); drillo (Italian); dril (Spanish); M. sphinx: Papio sphinx, mandrill; mandrill (Danish, French, German, Swedish); mandril (Dutch); mandrillit (Finnish); mandrillo (Italian); mandril (Spanish).

There are two monotypic species in the genus Mandrillus, the mandrill (M. sphinx) and the drill (M. leucophaeus), each with no subspecies (Groves 2005). For clarity, they will each be referred to here by their scientific names as opposed to their common names.

Conservation status:  Endangered (M. leucophaeus), Vulnerable (M. sphinx)

Life span: ~40 years (captive)
Total population: Unknown
Regions: Cameroon, Equatorial Guinea, Gabon, Nigeria, Republic of Congo
Gestation: M. leucophaeus: 179-182 days; M. sphinx: 175 days
Height: Unknown
Weight: M. leucophaeus: 32.3 kg (M), 11.7 kg (F); M. sphinx: 31.6 to 33.0 kg (M), 12.0 to 12.9 kg (F)

MORPHOLOGY

Drill
Mandrillus

Members of the genus Mandrillus are large-bodied primates that are instantly recognizable. M. sphinx have thick dark gray pelage, banded in black and reddish-yellow, while M. leucophaeus are greenish gray or brown overall with a whitish belly (Groves 2001; Ankel-Simons 2007). M. sphinx have an orange beard, while M. leucophaeus have a white beard (Groves 2001). The hairless face however, holds the most profound differences between the species. The face of M. sphinx is immediately recognizable, featuring an elongated snout with swollen blue ridges on top (4 or 5) and red nose and lips (Groves 2001; Ankel-Simons 2007). Female M. sphinx have far more subdued coloration in the face than do males, but can range from black to bright pink (Cousins 1984; Setchell et al. 2006). M. leucophaeus differ in their facial coloration, which is more subdued than in M. sphinx. Their lower lip is red, but the rest of the face is entirely shiny black, with smooth swollen ridges on the top of the elongated snout (Hill 1955; Groves 2001). There is a ruff of white hair around the face in M. leucophaeus (Cousins 1984). Male M. leucophaeus have red and blue colored anogenital regions, while male M. sphinx have strikingly multi-colored (red, pink, blue, scarlet, and purple) anogenital areas (Ankel-Simons 2007). All sexes and species of Mandrillus have pale pink ischial callosities (Ankel-Simons 2007). Individuals of the genus Mandrillus possess a glandular patch of skin (surrounded by bristly hairs) used in olfactory communication on their chests which is more pronounced and developed in dominant adult males (Hill 1970; Feistner 1991; Setchell & Dixson 2001a). In addition, adult male M. sphinx have 4.5 cm (1.8 in) long canines on average, compared to 1.0 cm in females (Leigh et al. 2005; 2008).

Drill
Mandrillus

Overall, body shape and size are similar in the two species of the genus (Grubb 1973). M. leucophaeus on average weigh about 32.3 kg (71.2 lb) (M) and 11.7 kg (25.8 lb) (F) and M. sphinx weigh on average 31.6-33.0 kg (69.7-72.8 lb) (M) and 12.0-12.9 kg (26.5-28.4 lb) (F) (reviewed in Smith & Jungers 1997; Jolly 2007; Marty et al. in press; Joanna Setchell pers. comm.). One M. sphinx female had a head and body length of 56.0 cm (22.0 in), while a M. leucophaeus female had a head and body length of 66.0 cm (26.0 in) (Napier 1981). Adult male mandrills (M. sphinx) weigh over three times what females weigh, indicating marked sexual dimorphism by body weight, the greatest dimorphism among the primates (Setchell et al. 2001; Leigh et al. 2008). M. leucophaeus are also highly sexually dimorphic (Elton & Morgan 2006).

Mandrillus spend a significant of their time on the ground and are predominantly terrestrial, mainly using the forest floor. Even then, they spend more time arboreally than baboons and may feed at all forest levels, including the canopy (Hoshino et al. 1984; Harrison 1988; Gonzalez-Kirchner & de la Maza 1996; Ankel-Simons 2007; Leigh et al. 2008). Time spent in trees however, is usually in levels nearer to the ground (Sabater Pí 1972). Terrestrially, they move through digitigrade quadrupedalism, and terrestrial and arboreal progressions are usually slow (Sabater Pí 1972; Ankel-Simons 2007). Other forms of arboreal locomotion are lateral jumps (Sabater Pí 1972).

In captivity, members of the genus Mandrillus have lived into their late thirties to forty years old (Weigl 2005). Under semi-free-ranging conditions at the Centre International de Recherce Médicales, Franceville (CIRMF), Gabon, males usually live for around 14 years, while females live at least 25 years (Setchell et al. 2005).

RANGE

CURRENT RANGE MAPS (IUCN REDLIST):
Mandrillus leucophaeus | Mandrillus sphinx

The ranges of M. sphinx and M. leucophaeus are incompletely known, but span the region between southern Congo and eastern Nigeria, separated by the Sanaga River in Cameroon, with M. leucophaeus north of this barrier and M. sphinx south of it (Harrison 1988).

M. leucophaeus is found in Cameroon, Nigeria, and Equatorial Guinea. However, its distribution in Equatorial Guinea is limited to Bioko Island, located in the Gulf of Guinea. The range is discontinuous, with the range on the mainland divided into a minimum of 11 areas, and the Bioko Island populations divided into at least two populations, occupying most of the southern part of the island (Gonzalez-Kirchner & de la Maza 1996; Gadsby & Jenkins 1997-1998; Oates & Butynski 2008a). They are present in the west and southwest of Cameroon (as far south as the Sanaga River) as well as limited to southeastern Nigeria (as far west as the Cross River) (Oates & Butynski 2008a). Their distribution in the interior is limited by savannah (Harrison 1988). M. leucophaeus might occur in Gabon, but evidence is unclear and is likely erroneous (Harrison 1988; Blom et al. 1992).

M. sphinx occur just south of the M. leucophaeus distribution, in Cameroon, Republic of Congo (not DRC), mainland Equatorial Guinea, and Gabon (Oates & Butynski 2008b). As one moves south from the Sanaga River, M. sphinx range in Equatorial Guinea, Gabon, and the Republic of Congo as far south as the Congo River, but not east of it (Oates & Butynski 2008b). In the east, M. sphinx are limited in Gabon by the Ivindo and Ogooue Rivers, in Cameroon by the Dja River, and in the southeast of their distribution by savannah (Oates & Butynski 2008b).

HABITAT

M. sphinx inhabits mainly tropical rain forests (including semi-deciduous lowland rainforest, closed-canopy lowland moist forest, and other primary and secondary rainforests often with very dense vegetation) and forest-savannah mosaic forests (never moving far into pure savannah), but also Marantaceae and rocky forest, as well as gallery forest within savannah areas, riparian forests, agricultural areas and even inundated forests and stream beds (Sabater Pí 1972; Hoshino et al. 1984; Hoshino 1985; Lahm 1986; Harrison 1988; Rogers et al. 1996; Tutin et al. 1997a; Matthews et al. 1998; Abernethy et al. 2002; Astaras et al. 2008). They sometimes also cross grassy areas within their forested habitats (Harrison 1988). M. leucophaeus are found in coastal forest, lowland forest, premontane forest, submontane forest, montane forest, and montane savannah, and as high as 2000 meters (6561.7 feet) above sea level (Wild et al. 2005; Astaras et al. 2008).

At the Lopé Reserve, Gabon, a habitat of M. sphinx, there are two dry seasons (one between December and February and one between June and September) with a total annual rainfall of 150.9 cm (59.4 in) (Abernethy et al. 2002). Temperatures are relatively constant year-round, usually ranging between 20 and 33°C (68 and 91.4°F) (Abernethy et al. 2002). At the Korup National Park (KNP), Cameroon, a habitat of M. leucophaeus, average rainfall is over 500 cm (196.9 in), with a wet season between May and October and a dry season between December and February. Similar to the Lopé Reserve, temperatures are relatively constant throughout the year, with average highs around 30.6°C (87.1°F) (Astaras et al. 2008).

In many ways, the often dense habitats of the genus Mandrillus have made research difficult, and as a result, little is known about certain aspects of their ecology and behavior (Hoshino et al. 1984; Jolly 2007).

ECOLOGY

Drill
Mandrillus

M. leucophaeus and M. sphinx have similar omnivorous diets (Rogers et al. 1996; Astaras et al. 2008). Mainland M. leucophaeus have been seen to consume seeds, fruits, insects, green leaves, and mushrooms, while Bioko Island M. leucophaeus eat fruits (58%), insects (25%) other vegetation including leaves, stems marrows (16%), and other invertebrates such as snails (1%) (Gonzalez-Kirchner & de la Maza 1996; Astaras et al. 2008). M. sphinx consume mostly plant matter, including predominantly fruit, but also leaves, lianas, bark, stems, fibers, animal foods, mushrooms, soils and other foods (Jouventin 1975; Hoshino 1985; Lahm 1986; Rogers et al. 1996). Over one hundred species of plant are consumed in all. Animal foods include predominantly invertebrates (ants, beetles, termites, crickets, spiders, snails and scorpions), as well as birds and eggs and the occasional vertebrate (including tortoises, frogs, porcupines, rats and shrews) (Hoshino 1985; Lahm 1986). For example, Lopé Reserve, Gabon, M. sphinx ate fruit (50.7%), seeds (26.0%), leaves (8.2%), pith (6.8%), flowers (2.7%), animal foods (4.1%) and other foods (1.4%) (Tutin et al. 1997a). There is evidence of probable M. sphinx predation on larger animals as well, including a juvenile bay duiker (Cephalophus dorsalis), a small antelope (Kudo & Mitani 1985).

There is some seasonal variation in the diet of M. sphinx. In Cameroon, fruit is the predominant food for the entire year, but between April and July is less available, and the proportions of other foods (such as leaves) in the diet increases (Hoshino 1985).

M. sphinx spend the night in trees, each night sleeping at a different site (Hoshino 1985). The species is diurnal, with activity starting in the morning, and lasting until the evening, when suitable sleeping trees are found and ascended (Jouventin 1975). In captivity, M. sphinx spend their days feeding (66%), moving (7%), stationary (12%) and in social activities (6%) (Chang et al. 1999).

Ranging information is limited and based on few observations. No annual data is available about ranging, but estimated daily paths of M. sphinx include 2.5-15.0 kilometers (1.6-9.3 miles) per day (one all-day follow at 8 kilometers (5.0 miles)) and estimates of home ranges are between 5 km² (1.9 mi²) and a very large 28 km² (10.8 mi²) (very rough estimates put the value as high as 50 km²(19.3 mi²)) (Jouventin 1975; Hoshino et al. 1984; Hoshino 1985; reviewed in Harrison 1988). To illustrate how variable and incomplete knowledge of ranging is, one horde (more than 600 individuals) of M. sphinx moved only 150 m (492.1 ft) on a single day, while on another it moved 3 km (1.9 mi) (Rogers et al. 1996). The home range of M. leucophaeus is unknown (Astaras et al. 2008).

M. sphinx can be sympatric with a number of other non-human primates. For example, in Gabon, they are sympatric with a number of guenons (Cercopithecus spp.), talapoins (Miopithecus talopoin), mangabeys (Cercocebus spp.), colobus monkeys (Colobus satanas), as well as apes (Pan troglodytes & Gorilla gorilla) (Harrison 1988; Tutin et al. 1997a).

Leopards (Panthera pardus) are known predators of M. sphinx and crowned eagles (Stephanoaetus coronatus) and various snakes probably also take the species (Jouventin 1975; Harrison 1988; Henschel et al. 2005).

Content last modified: October 14, 2009

Written by Kurt Gron. Reviewed by Joanna Setchell.

Cite this page as:
Gron KJ. 2009 October 14. Primate Factsheets: Drill (Mandrillus) Taxonomy, Morphology, & Ecology . <http://pin.primate.wisc.edu/factsheets/entry/drill/taxon>. Accessed 2020 July 30.

SOCIAL ORGANIZATION AND BEHAVIOR

Much of the socio-ecology of Mandrillus is still unclear, especially when it comes to M. leucophaeus, the lesser known species. Also, there is some conflicting information about group structure within the genus. Some researchers suppose a multi-tier organization with subunits (one-male units) aggregating into larger units (hordes) and others observe no suborganization within large aggregations and only a seasonal male presence in groups (Gartlan 1970; Hoshino et al. 1984; Harrison 1988; Forthman et al. 1992; Rogers et al. 1996; Abernethy et al. 2002; Jolly 2007; Astaras et al. 2008). Another option may be daily or temporary fisson-fusion of larger social groups, and further research is required into the organization of smaller groupings of Mandrillus (Astaras et al. 2008).

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Mandrillus

The most pronounced aspect of M. sphinx social organization, however, is the potential for extremely large stable groups in the wild (Abernethy et al. 2002; Jolly 2007). These stable groups, termed “hordes,” often reach into hundreds of members; in one study, they averaged 620 individuals and can be as large as 845 (Sabater Pí 1972; Jouventin 1975; Harrison 1988; Rogers et al. 1996; Tutin et al. 1997b; Abernethy et al. 2002). Data from the wild suggest that adult males only enter hordes during female seasonal sexual cycling (about three months of the year) and leave after, but group size is not correlated with reproduction. Thus, the only annually resident members of M. sphinx groups are adult females and dependent offspring, making the social system female-led (Abernethy et al. 2002). However, social groups can also be quite variable, with smaller groups (less than 50 individuals) also rarely recorded in addition to hordes, as well as solitary males, but never all male (bachelor) groups (Sabater Pí 1972; Jouventin 1975; Hoshino et al. 1984; Harrison 1988; Rogers et al. 1996; Abernethy et al. 2002). Outside of the mating season, males are solitary (Abernethy et al. 2002). Under semi-free-ranging conditions at CIRMF, breeding is moderately seasonal, with 63% of female periovulatory periods occurring between July and September (Setchell & Wickings 2004). There is a corresponding birth peak between January and March, and at least some males appear to remain with the social group year-round, although there is space for them to be solitary in the naturalistic enclosures at CIRMF (Setchell et al. 2002; J. Setchell pers. comm.).

Recorded average group sizes in M. leucophaeus included 93.1, 52.3, and 9.1 individuals, but observations have recorded groups into the hundreds of members and as large as an estimated 400 individuals (Gartlan 1970; Dunn & Okon 2003 cited in Astaras et al. 2008; Wild et al. 2005; Astaras et al. 2008). It is possible that true group sizes are even larger (Wild et al. 2005). On Bioko Island, it appears that M. leucophaeus groups are smaller than on the mainland, usually less than 20 individuals (Gonzalez-Kirchner & de la Maza 1996). Solitary males are sometimes encountered and there are no seasonal patterns of group size (Wild et al. 2005). It is unclear as to the exact social organization of M. leucophaeus, but multimale groups and group fission and fusion have been observed (Astaras et al. 2008).

Male mandrills at CIRMF reach sexual maturity at about 4 years old, and are capable of siring at 4.9 years (Setchell & DIxson 2002; Setchell et al. 2005). They become peripheral to the social group at about 6 years old, and data from the wild suggest that wild males emigrate from their natal group at about this age (Harrison 1988; Abernethy et al. 2002; Setchell et al. 2006). In captivity, M. leucophaeus males also reach maturity around six years old (Böer 1987). Males of both species reach full size at about 9 or 10 years (Setchell et al. 2006; Marty et al. in press). Female mandrills at CIRMF cycle for the first time at an average age of 3.6 years, first give birth at an average of 4.2 years, and reach full size at about 7 years old (Setchell et al. 2001; 2002; Setchell & Wickings 2004).

When by themselves in a captive setting, solitary M. sphinx may groom itself (autogroom), bounce upon surfaces, play, forage, or mark with its sternal gland. Captive social behaviors include allogrooming, solicitation of grooming (usually by presenting the posterior or the neck or armpit), playing, presenting, mounting, threatening, attacking, and “smiling”. Threats are commonly conveyed by bobbing the head (Mellen et al. 1981).

In semi-captive M. sphinx, affiliative relationships between adult males are extremely infrequent and males form linear dominance hierarchies, with a single alpha male at the top (Setchell & Wickings 2005; Setchell et al. 2005a). The top-ranking male can be often identified as the male individual with the brightest red coloration with roughly less and less red coloration in decreasingly ranked males (Setchell & Wickings 2005; Setchell et al. 2008). Early studies, based on six males, suggested that there are two phases of M. sphinx adult male; “fatted” (with brighter and more pronounced coloration as well as higher cutaneous gland secretion and an increase in “fattedness” of the rump) and “non-fatted” (with less pronounced coloration and “fattedness” of the rump) (Dixson et al. 1993). “Fatted” and “non-fatted” males did not differ in body mass, merely in the distribution of weight in the body (Wickings & Dixon 1992). However, subsequent studies suggest that there is a continuum between paler and brighter males, and that color is not necessarily associated with “fattedness” (Setchell & Dixson 2001b). When alpha-male status is attained, a male undergoes physical changes and becomes more brightly colored with higher testosterone, and becomes more social (Setchell & Dixson 2001b). With a loss of status, the reverse changes occur (Setchell & Dixson 2001b; Setchell et al. 2008).

When semi-captive adult males encounter one another, they may enter a “stand-off” in which they remain near each other while anxious or stressed, and may threaten each other (Setchell & Wickings 2005). Such “stand-offs” can end either without resolution, with one individual leaving, or with physical contact, and are more likely to occur between closely-ranked, physically similar males (Setchell & Wickings 2005). Males show submission by avoidance, fleeing, presentation of the hindquarters, or screaming. Threats are conveyed through “stares,” “head-bobs,” “ground-slaps,” “threat-grunts,” lunges and chases. Confrontations between males can become violent and can even result in the death of individuals (Setchell & Wickings 2005). The M. sphinx “grin” appears to have a non-agonistic function, much as the captive M. leucophaeus “smile” indicates a friendly approach or benign intentions (Hearn et al. 1988; Setchell & Wickings 2005; Otovic 2007).

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Mandrillus

In semi-captivity, several female mandrills were observed to attack a wounded adult male, possibly to exclude it from group membership and indicating some female control over group membership (Setchell et al. 2006b).

REPRODUCTION

Most data on reproduction in the genus Mandrillus come from a long-term semi-captive population of M. sphinx in Gabon. There is little data on reproduction in wild, free-ranging groups. In semi-captivity, M. sphinx have a polygyandrous mating system (Setchell et al. 2002).

In wild M. sphinx in Gabon, there is a discrete mating season during which females exhibit sexual swellings, usually between June and November with a corresponding birth season between January and April (Jouventin 1975; Abernethy et al. 2002). Outside of the mating system, adult males leave M. sphinx groups, only returning at the onset of the subsequent mating season (Abernethy et al. 2002). In semi-captivity at CIRMF, a mating peak is also observed between July and September with a corresponding birth peak from January to March, and males do not necessarily leave the social group outside the mating season (Setchell et al. 2002; Setchell & Wickings 2004).

In captivity, female M. sphinx present by aiming their bodies away from the male and looking back towards the male over their shoulders (Mellen et al. 1981). The copulatory posture is dorsalventral, with the male behind the female (she may be straight-legged, with the ventrum on the ground or somewhere in-between), forearms holding in front of the pelvis and feet on the ground (Mellen et al. 1981). Copulatory sperm-plugs are formed (Wickings & Dixson 1992).

M. sphinx females in a semi-captive group first give birth at an average age of 4.2 years old with higher-ranking females reproducing earlier than lower-ranking females (Setchell & Wickings 2004; Setchell et al. 2005b). Males start to reproduce significantly later, starting at an average of 11.6 years old, although they are capable of reproducing from 4 years old (Setchell et al. 2005b). In a long-term study of a semi-captive population at CIRMF, all females reproduced while only a third of the males were successful (Setchell et al. 2005b).

Gestation averages 175 days in M. sphinx with an inter-birth interval in semi-captivity of 405 days on average, although values vary slightly between specific captive populations (Setchell et al. 2002; but see also Bettinger et al. 1995). M. leucophaeus have a gestation period between 179-182 days and an inter-birth interval of 17-19 months (Böer 1987). The estrous cycle in M. leucophaeus is 33 days, while in M. sphinx it is 35 or 38 days (Harvey & Clutton-Brock 1985; Setchell & Wickings 2004).

In a semi-captive group, roughly two-thirds of offspring were sired by dominant males (Setchell et al. 2005a). Males mate-guard higher ranking females more than lower ranking females (Setchell & Wickings 2006). The larger the canine teeth of an M. sphinx, the higher reproductive success the animal is likely to have (Leigh et al. 2008).

PARENTAL CARE

As expected in populations with a mating season, wild M. sphinx in Gabon has a birth season between January and April (Jouventin 1975). In semi-captivity, M. sphinx have a birth season from January to March and give birth at night only (Feistner 1992; Setchell et al. 2002). At birth female M. leucophaeus weigh 722 g (25.5 oz) while female M. sphinx weigh 890 g (31.4 oz) and M. sphinx males 906g (32.0 oz) (Smith & Leigh 1998). In general, there is little difference between the birth weights of the sexes (Wickings & Dixson 1992). The face of the infant M. leucophaeus is light in color, fading to black by 8 months old (Böer 1987). M. sphinx infants are born either gray or white with a dark stripe down the back. The top of the head is black with a pink face and the torso and limbs have bluish skin (Feistner 1992).

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Mandrillus

One M. sphinx infant was first seen away from its mother at 20 days of age, and started trying solid foods at around 35 days old. By four months old, the infant left its mother often and for long periods. The infant was weaned at 8 months old (Carman 1979). M. leucophaeus are weaned by 15-16 months of age (Böer 1987).

COMMUNICATION

One of the most conspicuous of displays in M. sphinx is the “silent bared-teeth face” (also called “smiling” and “grinning”), in which the animal exposes its teeth by curling back the lips, erects the crest of the head, while shaking the head. While multiple interpretations have been offered for this display, it most likely has a conciliatory, non-aggressive or peaceful function (Bout & Thierry 2005; Laidre & Yorzinski 2005; Setchell & Wickings 2005). The “crest-raise” signal (erection of the sagittal crest) may be related to the “silent bared-teeth face” signal in function and may grade into it (Laidre & Yorzinski 2005). Submission is signaled by a presentation of the rump. Aggression is signaled by staring, head-bobbing, and ground-slapping (Setchell & Wickings 2005).

Facial color in M. sphinx females may communicate reproductive information to others – color is brighter during the follicular phase than during the luteal phase, varies across gestation, and peaks at four and eight weeks post-parturition (Setchell et al. 2006a). In addition, facial redness in male M. sphinx communicates competitive information to other males and information about male fitness to females (Setchell et al. 2008).

Wild M. sphinx vocalizations can be divided into roughly 11 categories, divided between long distance calls and short distance calls (Kudo 1987). Long distance calls include the “2-phase grunt,” “roar,” and “crowing”. Short distance calls include the “yak,” “grunt,” “k-alarm,” “k-sound,” “scream,” “girney,” and “grind” (Kudo 1987). The “2-phase grunt” is the most commonly emitted vocalization, even though it is only emitted by adult males, and may indicate the adult male’s role in group cohesion. Both “crowing” and the “2-phase grunt” may function as long-distance contact calls and serve to communicate information about the locations of group members (Kudo 1987; Harrison 1988). When with sexually receptive females, wild M. sphinx males may emit “grunt” vocalizations continuously, but never when alone (Abernethy et al. 2002). Males also emit “threat-grunts” to other males to indicate aggression (Setchell & Wickings 2005).

Both members of the genus Mandrillus possess a sternal gland (Hill 1970; Feistner 1991). Both female and male M. sphinx use this gland to scent mark by grasping a substrate or object and rubbing their chest upon it (Mellen et al. 1981; Feistner 1991). Scent marking may help reinforce dominance status or help a M. sphinx orient itself within its home range (Feistner 1991).

Content last modified: October 14, 2009

Written by Kurt Gron. Reviewed by Joanna Setchell.

Cite this page as:
Gron KJ. 2009 October 14. Primate Factsheets: Drill (Mandrillus) Behavior . <http://pin.primate.wisc.edu/factsheets/entry/drill/behav>. Accessed 2020 July 30.

INTERNATIONAL STATUS

CITES: Appendix I (What is CITES?)
IUCN Red List: M. leucophaeus: EN; M. sphinx: VU (What is Red List?)
Key: EN = Endangered, VU = Vulnerable
(Click on species name to see IUCN Red List entry, including detailed status assessment information.)

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Mandrillus

It is illegal to kill M. leucophaeus and punishable by large fines and prison, although such penalties have never been imposed in practice and enforcement is often difficult or nonexistent in practice, even in protected areas (Wild et al. 2005).

Reintroduction projects of M. sphinx in Gabon have been undertaken, with some individuals being successfully introduced into the wild, integrating with wild individuals and becoming self-sufficient. This has provided critical experience for potential future reintroduction projects (Peignot et al. 2008).

CONSERVATION THREATS

Threat: Human-Induced Habitat Loss and Degradation

Habitat loss for various purposes is a significant threat to the genus Mandrillus. Causes for such deforestation or habitat degradation may include forest clearance for cattle grazing and agriculture, and expanding human settlements (Cox 1997; Wild et al. 2005). Further, roads constructed for other industries can exacerbate threats to Mandrillus populations, by increasing human populations as well as bushmeat commerce and consumption (Harrison 1988; Steiner et al. 2002-2003). Logging roads also isolate populations, and alter their ecology (Gadsby & Jenkins Jr. 1997-1998).

Threat: Harvesting (hunting/gathering)

Hunting of mainland M. leucophaeus occurs often and is probably the biggest threat to the species. Hunting can be and has been quite intense, and has the potential to or has significantly reduced populations (Gadsby 1992; Wild et al. 2005; Willcox & Nambu 2007). In other cases, hunting has fragmented populations significantly altering their ecology. In one instance from the 1990’s, several hunters killed over one hundred individuals in only several hunting trips. However, local traditional hunting bans have had some success in curbing the cull (Wild et al. 2005). Intensive hunting of M. leucophaeus for bushmeat also occurs on Bioko Island, Equatorial Guinea, where carcasses can be found for sale in markets, and is considered a delicacy (Gonzalez-Kirchner & de la Maza 1996; Albrechtsen et al. 2006).

Often drill and mandrill hunting is with dogs, which Mandrillus try to avoid by fleeing into trees where they are then killed with firearms, as they cannot easily move from tree to tree (Harrison 1988; Mitani 1990; Gadsby 1992; Gonzalez-Kirchner & de la Maza 1996; Cox 1997; Steiner et al. 2002-2003). Sometimes entire groups can be killed in this fashion and the species are particularly vulnerable to commercial hunting because of the efficacy of this method (Gadsby & Jenkins Jr. 1997-1998). In these cases, the take may be skewed towards adult males as they are significantly larger than females (and represent more meat), and as a result, both social and reproductive dynamics of the species are particularly affected (Mitani 1990; Steiner et al. 2002-2003). Hunting at a particular locality may also be by both local and non-local individuals and the cull may be locally or non-locally consumed (Steiner et al. 2002-2003). Non-local hunters in Cameroon hunt M. leucophaeus intensively and in a systematic fashion (Gadsby & Jenkins Jr. 1997-1998).

Threat: Persecution

M. sphinx sometimes crop-raid on plantain crops and are sometimes killed as pests (Mitani 1990).

LINKS TO MORE ABOUT CONSERVATION

CONSERVATION INFORMATION

CONSERVATION NEWS

ORGANIZATIONS INVOLVED IN Mandrillus CONSERVATION

Content last modified: October 14, 2009

Written by Kurt Gron. Reviewed by Joanna Setchell.

Cite this page as:
Gron KJ. 2009 October 14. Primate Factsheets: Drill (Mandrillus) Conservation . <http://pin.primate.wisc.edu/factsheets/entry/drill/cons>. Accessed 2020 July 30.

 

The following references were used in the writing of this factsheet. To find current references for Mandrillus sphinx, search PrimateLit. To find current references for M. leucophaeus, search PrimateLit.

REFERENCES

Abernethy KA, White LJT, Wickings EJ. 2002. Hordes of mandrills (Mandrillus sphinx): extreme group size and seasonal male presence. J Zool (Lond.) 258(1):131-7.

Albrechtsen L, Fa JE, Barry B, Macdonald DW. 2006. Contrasts in availability and consumption of animal protein in Bioko Island, West Africa: the role of bushmeat. Environ Conserv 32(4):340-8.

Ankel-Simons F. 2007. Primate Anatomy: an introduction, 3rd Edition. San Diego: Elsevier Acad Pr. 724 p.

Drill artwork
Mandrillus

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Hoshino J. 1985. Feeding ecology of mandrills (Mandrillus sphinx) in Campo Animal Reserve, Cameroon. Primates 26(3):248-73.

Hoshino J, Mori A, Kudo H, Kawai M. 1984. Preliminary report on the grouping of mandrills (Mandrillus sphinx) in Cameroon. Primates 25(3):295-307.

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Jouventin P. 1975. Observations sur la socio-ecologie du mandrill. Terre et la Vie 29:493-532.

Kudo H, Mitani M. 1985. New record of predatory behavior by the mandrill in Cameroon. Primates 26(2):161-7.

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Leigh SR, Setchell JM, Charpentier M, Knapp LA, Wickings EJ. 2008. Canine tooth size and fitness in male mandrills (Mandrillus sphinx). J Hum Evol 55(1):75-85.

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Setchell JM, Lee PC, Wickings EJ, Dixon AF. 2001. Growth and ontogeny of sexual size dimorphism in the mandrill (Mandrillus sphinx). Am J Phys Anth 115(4):349-60.

Setchell JM, Wickings EJ. 2006. Mate choice in male mandrills (Mandrillus sphinx). Ethology 112(1):91-9.

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Setchell JM, Wickings EJ. 2004. Social and seasonal influences on the reproductive cycle in female mandrills (Mandrillus sphinx). Am J Phys Anth 125(1):73-84.

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Wickings EJ, Dixson AF. 1992. Development from birth to sexual maturity in a semi-free-ranging colony of mandrills (Mandrillus sphinx) in Gabon. J Reprod Fert 95(1):129-38.

Wild C, Morgan BJ, Dixson A. 2005. Conservation of drill populations in Bakossiland, Cameroon: historical trends and current status. Int J Primatol 26(4):759-73.

Willcox AS, Nambu DM. 2007. Wildlife hunting practices and bushmeat dynamics of the Banyangi and Mbo people of southwestern Cameroon. Biol Conserv 134(2):251-61.

Content last modified: October 14, 2009

IMAGES

Mandrillus leucophaeus
Photo: Irwin Bernstein
Mandrillus leucophaeus
Photo: J. Stephen Gartlan
Mandrillus leucophaeus
Photo: Verena Behringer
Mandrillus leucophaeus
Photo: Verena Behringer

Mandrillus sphinx
Photo: Irwin S. Bernstein
Mandrillus sphinx
Photo: Joanna Setchell
Mandrillus sphinx
Photo: Joanna Setchell
Mandrillus sphinx
Photo: Joanna Setchell
Mandrillus sphinx
Photo: Joanna Setchell
Mandrillus sphinx
Photo: Joanna Setchell
Mandrillus sphinx
Photo: Primates in Art & Illustration Collection
Mandrillus sphinx
Photo: Verena Behringer
Mandrillus sphinx
Photo: Verena Behringer
Mandrillus sphinx
Photo: Verena Behringer

 

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