Monkeys are a diverse order of primates, exhibiting a wide variety in size, form, and behavior across the globe. Found primarily in tropical Africa, Asia, and the Americas, they range from tiny marmosets to much larger species. This wide spectrum of sizes naturally leads to questions about which monkey species is the largest. Understanding the largest monkey’s dimensions reveals adaptations within the primate lineage.
The Mandrill: The Largest Monkey
The mandrill (Mandrillus sphinx) is the largest monkey species in the world. This Old World monkey exhibits significant sexual dimorphism, with males and females having distinct physical differences, particularly in size. Adult male mandrills typically have a head-body length of 70 to 95 centimeters (28 to 37 inches) and weigh 19 to 30 kilograms (42 to 66 pounds). Some dominant males have been recorded weighing up to 37 kilograms (81.6 pounds).
Female mandrills are considerably smaller, usually measuring 55 to 70 centimeters (22 to 28 inches) in head-body length and weighing 10 to 15 kilograms (22 to 33 pounds). Males are two to three times larger than females. Their robust build and powerful limbs contribute to their large size.
Distinctive Features of the Mandrill
Beyond their substantial size, mandrills are known for their strikingly colorful appearance. Adult males display vivid blue and purple ridges on the sides of their muzzles, with a bright red stripe down their nose and around their nostrils. Their lips are also red, and they often have a yellow-orange beard.
Their posterior skin, including the rump and genitals, exhibits shades of red, pink, blue, and purple. Females generally have more subdued coloring, though some can show stronger hues. Mandrills also possess long, thick canine teeth, especially in males, whose canines can reach 4.5 centimeters (1.8 inches), compared to 1 centimeter (0.39 inches) in females. Their fur is typically grizzled or banded olive-brown, with lighter fur on their undersides.
Mandrill Habitat and Social Structure
Mandrills are native to west-central Africa, primarily inhabiting tropical rainforests and forested savannas. Their geographic range includes southern Cameroon, mainland Equatorial Guinea, Gabon, and parts of the Republic of the Congo. These semi-terrestrial monkeys spend much of their day foraging on the forest floor, but also climb trees for shelter at night.
Mandrills are omnivores, with a diverse diet including fruits, seeds, leaves, roots, fungi, insects, snails, worms, frogs, lizards, and small vertebrates like birds and rodents. They are highly social, living in large, stable groups known as “hordes” that can comprise hundreds of individuals. Some recorded hordes have numbered over 800 mandrills, potentially making them the largest cohesive groups of wild primates. These multi-male and multi-female groups typically have females forming the core, while adult males may be more solitary, joining the group during breeding season.