Mandrill
The mandrill is a large Old World monkey native to west central Africa. It is one of the most colorful mammals in the world, with red and blue skin on its face and posterior. The species is sexually dimorphic, as males have a larger body, longer canine teeth and brighter coloring. Its closest living relative is the drill, with which it shares the genus Mandrillus. Both species were traditionally thought to be baboons, but further evidence has shown that they are more closely related to white-eyelid mangabeys.
Mandrills mainly live in tropical rainforests but will also travel across savannas. They are active during the day and spend most of their time on the ground. Their preferred foods are fruit and seeds, but mandrills will consume leaves, piths, mushrooms, and animals from insects to juvenile bay duiker. Mandrills live in large, stable groups known as "hordes" which can number in the hundreds. Females form the core of these groups, while adult males are solitary and only reunite with the larger groups during the breeding season. Dominant males have the most vibrant colors and fattest flanks and rumps, and have the most success siring young.
The mandrill is classified as vulnerable on the IUCN Red List. Its biggest threats are habitat destruction and hunting for bushmeat. Gabon is considered the stronghold for the species. Its habitat has declined in Cameroon and Equatorial Guinea, while its range in the Republic of the Congo is limited.
Etymology
The word mandrill is derived from the English words man and drill—the latter meaning or and being West African in origin—and dated to 1744. The name appears to have originally referred to chimpanzees. The first scholar to record the name for the colorful monkey was Georges-Louis Buffon in 1766. It was called the "tufted ape", "great baboon" and "ribbernosed baboon" by Thomas Pennant in A Synopsis of Quadrupeds and A History of Quadrupeds.Taxonomy
The mandrill was first scientifically depicted in Historia animalium by Conrad Gessner, who considered it a kind of hyena. The species was formally classified by Carl Linnaeus as Simia sphinx in 1758. Its current generic name Mandrillus was coined by Ferdinand Ritgen in 1824.Historically, some scientists placed the mandrill and the closely related drill in the baboon genus Papio. Morphological and genetic studies in the late 20th and early 21st centuries found a closer relationship to white-eyelid mangabeys of the genus Cercocebus. Some have even proposed that the mandrill and drill belong to Cercocebus. Two genetic studies in 2011 clarified Mandrillus and Cercocebus as separate sister lineages. The two genera split around 4.5 million years ago while the mandrill and drill split approximately 3.17 mya. Fossils of Mandrillus have not been found.
Some authorities have divided mandrill populations into subspecies: the northern mandrill and the southern mandrill. A proposed third subspecies, M. s. insularis, was based on the mistaken belief that mandrills are present on Bioko Island. The consensus is that mandrills belong to one subspecies.
Cytochrome-b sequences suggest that mandrill populations north and south of the Ogooué River split 800,000 years ago and belong to distinct haplogroups. This divergence appears to have also led to the splitting of the mandrill strain of the simian immunodeficiency virus. The draft genome of the mandrill was published in 2020, with a reported genome size of 2.90 giga–base-pairs and high levels of heterozygosity.
Characteristics
The mandrill has a stocky body with a large head and muzzle, as well as a short and stumpy tail. The limbs are evenly sized and the fingers and toes are more elongated than those in baboons, with a more opposable big toe on the feet. The mandrill is the most sexually dimorphic primate, and it is the largest monkey. Females are less stocky and have shorter, flatter snouts. Males have a head-body length and weigh while females have a head-body length and weigh. Most of the teeth are larger in males, and the canine teeth reach up to and long for males and females respectively. Both sexes have long tails.The coat of the mandrill is primarily grizzled or banded olive-brown with a yellow-orange beard and sparse, light hairs on its underside. The lips are surrounded by stiff white whiskers, and white bare skin exists behind the ears. Male mandrills have a "crest" of long hairs on the head and neck, while both sexes have chest glands which are covered by long hairs. The face, rump and genitals have less hair. The mandrill has a red line running down the middle of their face which connects to their red nose. On either side of the line, the skin is blue and grooved. In males, the blue skin is supported by ridged bone swellings. Females have more subdued facial coloring, but this can vary between individuals with some having stronger red and blue hues and others being darker or almost black. In males, the rump and areas around the genitals are multi-colored, consisting of red, pink, blue and purple skin, with a red penis shaft and violet scrotum. The genital and anal areas of the female are red.
The mandrill is among the most colorful mammals. Charles Darwin wrote in The Descent of Man: "no other member of the whole class of mammals is coloured in so extraordinary a manner as the adult male mandrill". The red coloration is created by blood vessels near the surface of the skin, while the blue is a form of structural coloration caused by parallel arrangements of collagen fibers. The blue ridges on males contrast with both the red facial hues and the green foliage of their environment, helping them stand out to other individuals. The darker and more subdued coloring of female faces is caused by melanin.
Ecology
The mandrill lives in west-central Africa, including southern Cameroon, mainland Equatorial Guinea, Gabon and parts of the Republic of the Congo. Its range is bounded by the Sanaga River to the north and the Ogooué and Ivindo Rivers to the east. It does not appear to share habitat with the drill, as the two species are separated by the Sanaga River. Mandrills live in tropical rainforests, generally preferring primary forests over secondary forests. They also live in patchy gallery forests surrounded by savanna and travel across grass areas within their forest habitats. They have also been recorded in mountainous areas, near rivers and in cultivated fields.Mandrills prefer thick bush dominated by perennial plants like gingers and plants of the genera Brillantaisia and Phaulopsis. They mainly dwell on the ground, but feed as high as the canopy. Both mandrills and drills are more arboreal than baboons. Mandrills may aggregate or compete with other primates such as talapoins, guenons, mangabeys, black-and-white colobuses, chimpanzees, and gorillas.
Diet
The mandrill is an omnivore. The core of its diet consists of plants, of which it eats over a hundred species. In Lopé National Park, the mandrill's diet was composed of fruit, seeds, leaves, pith, flowers, and animal matter, with other foods making up the remaining 1.4%. During the wet season, mandrills forage in continuous forest, when fruit is most available, while during the dry season they feed in gallery forests and at the borders of savannas and forests.The mandrill's preferred fruits include those of the cashew species Pseudospondias microcarpa, the coffee species Nauclea diderrichii and the wort species Psorospermum febrifugum. Mandrills consume more seeds than many other primate species. Adult male mandrills are one of the few primates capable of biting through the hard shell of Detarium microcarpum seeds. For vegetation, they mostly eat the young leaves, shoots and piths of monocot plants. In particular, mandrills consume leaves from the arrowroots Haumania liebrechtsiana and Trachyphrynium braunianum, as well as the piths of ginger plants like Renealmia macrocolia and species in the genus Aframomum. They are also known to consume mushrooms.
The rest of a mandrill's diet is largely made up of invertebrates, particularly ants, termites, crickets, spiders, snails, and scorpions. They also eat birds and their eggs, frogs and rodents. Mandrills have been recorded preying on larger vertebrates such as juvenile bay duikers. Such prey is killed with a bite to the head followed by pulling off the hind limbs and tearing open the belly. Individuals may cooperate during hunting and share kills.
Predators, parasites and pathogens
s may prey on mandrills, as traces of mandrill have been found in their feces. Other potential predators include African rock pythons, crowned eagles and chimpanzees. Leopards are a threat to all individuals, while eagles are only threats to the young. In a study where a mandrill group was exposed to models of leopards and crown eagles, the leopard models tended to cause the mandrills to flee up trees while the eagles were more likely to drive them to take cover. The dominant male did not flee from either model types; in the case of the leopards, he paced around while looking in their direction. Alarm calls were more commonly heard in response to leopards than eagles.Mandrills can become infected with gastrointestinal parasites, such as nematodes and protozoa. Tumbu fly larvae may live under the skin and individuals that walk through grassland can get infested with ticks. Blood parasites include the malaria-causing Plasmodium and the nematode Loa loa, which is transmitted by bites from deer flies. Wild mandrills have tested positive for SIV, enteroviruses of the species EV-J and astroviruses, including a human variant.