Mandrills (Mandrillus sphinx) are Old World monkeys, which are closely related to drills and baboons. They are perhaps the most colorful of all the mammalian species known to us. These colorful features make them distinct from others. However, like many other species, the colors are more prominent in adult males. An average adult male has double the body weight of an average adult female. The females are noticeably smaller, and have dull body colors. Let us take a look at some interesting facts about mandrill monkeys. You can identify a mandrill from its distinct characteristics, especially the long muzzle with the red stripe in between blue ridges. Even the nostril and the lips are bright red. The animal has sunken eyes, prominent brow ridges, red fur patches above the eyes, and a hairless face. The fur of this monkey is grayish or olive-colored. The mandrill monkey has a yellow beard, white tuffs, and a white belly. The colors turn brighter, as the male monkey reaches adolescence. Among the males, the dominant ones are found to be more colorful than others. The dominant mandrill is found to have high levels of testosterone. It has also been observed that, these colors become more pronounced, when the animal gets excited. It has a colorful rump with shades of red, pink, and blue. Like baboons, mandrills have toughened, cushion-like, hairless skin on their rump. Known as ischial callosities, this skin formation makes it convenient for these monkeys to sleep, while sitting upright. This is one of the adaptations of mandrill monkeys that have the habit of sleeping on tree branches, in a sitting position. Both males and females have chest glands that release scents, which are used for attracting mates through olfactory communication. This monkey has a short, vestigial tail. Another characteristic feature of a mandrill monkey is its sharp and long canine teeth, which can grow up to 6.5 centimeters in length. An average adult male mandrill weighs around 33 kilograms, whereas an adult female weighs around 12 kilograms. Male mandrills measure around 32 to 36 inches long, while females have a body length of 22 to 26 inches. Mandrills are natives to the central and western regions of Africa. They are found in Cameroon, Gabon, Equatorial Guinea, and Congo. The natural habitat of mandrills include the rainforests and woodlands. Being exclusively terrestrial primates, they prefer to spend most of their time on the forest floor. Nevertheless, they climb large trees and sleep on the branches for safety. They are also seen in rocky forests, stream beds, and grasslands. At times, they may enter cultivated areas and damage crops. The diet of these omnivorous monkeys consists of a wide range of fruits, roots, other vegetative parts, mushrooms, insects, small amphibians, reptiles, and other animals. While fruits comprise the main diet of mandrills, they also feed on considerable amounts of seeds, leaves, and other plant matter. Only 4% of their diet consists of animal matter, which includes spiders, ants, termites, snails, scorpions, beetles, birds, frogs, rats, and porcupines. They may feed on eggs of other animals and birds. Sometimes, they attack bigger animals, and kill them by biting the nape. Just like other large rainforest animals, they wander on the forest floor in search of food. An adaptive feature of these large primates is their ability to store small amounts of food in their cheek pouches. Mandrills live in groups known as 'hordes'. A single group may comprise as many as 1,000 individuals, mostly females and their young ones. Although they are social animals, male mandrills prefer to live a solitary life. Occasionally, they do form groups and forage together with females. However, most of the large mandrill groups consist of adult females and juveniles. The dominant male enters a horde, during the period of mating that extends up to three months. It has been observed that, the females of a horde share a strong bonding. The mothers are more attached to their daughters than their sons. The females spend their time foraging, playing, and grooming each other. Fights are very rare among the females of the group. Mandrills become sexually mature at the age of three to four years. While the dominant male is brightly colored, other males (with pale colors) too enter the horde and engage in mating. However, only the dominant male succeeds in producing offspring. The males in the group engage in deadly fights as a part of their struggle to gain dominance. Like males, each horde has dominant females, who are more likely to get pregnant. According to a recent study, female mandrills have the ability to choose the dominant male, whom they identify with his scent and color. The gestation period is 145 days, after which a single baby is born. The mandrill baby is hairy and is born with open eyes. It has a pink skin and black hair. The color of the skin and hair remains the same for the first two months. While daughters spend the rest of their life with their mothers, sons become solitary after attaining sexual maturity. The mother as well as her female relatives take care of the young one. It is believed that mandrills live up to 25 years in the wild. In captivity, these monkeys can survive for around 30 years. In the wild, mandrills are mainly threatened by leopards and pythons. However, humans are the main threat for these animals, which are hunted for their meat. Loss of rainforest habitat is another reason for their dwindling population. These monkeys are classified as 'vulnerable', by the International Union for Conservation of Nature (IUCN).