Mandrill

Mandrills live in Africa.

They live in warm, wet rainforests near the Atlantic Ocean. They walk on the forest floor and sleep up in the trees.

Mandrills live in the rainforests of west-central Africa, in Cameroon, Equatorial Guinea, Gabon and the Republic of the Congo. Most live in evergreen forest within about 100 to 300 kilometers of the Atlantic coast, and the largest populations are in Gabon.

A big river called the Ogooué runs through their range and splits mandrills into two separate populations, north and south. Mandrills avoid marshes and thick tangles of bushes, but they will cross a patch of open grassland to reach another piece of forest.

The IUCN places mandrills from the Sanaga River in Cameroon south through mainland Equatorial Guinea and much of Gabon to the Kouilou and Congo rivers in the Republic of the Congo, limited inland by the lower Ivindo and Ogooué; camera traps have extended the known range to the Dja Biosphere Reserve and Batéké Plateaux National Park. The Ogooué divides two genetically distinct populations.

Mandrills use the evergreen rainforest that stretches 100 to 300 kilometers inland from the Atlantic, as well as montane and secondary forest, crossing savanna gaps up to 180 meters wide. Intact forest supports about 10 mandrills per square kilometer, far fewer where hunting has gone on for a long time.

Mandrills eat lots of different foods.

They eat fruit, seeds, leaves and roots. They also eat insects. They can stuff food into their cheeks to eat later!

Mandrills are omnivores, so they eat both plants and animals. Their menu includes fruit, seeds, buds, leaves, roots, mushrooms, insects and small animals such as reptiles, amphibians, crabs and fish. Seeds are an especially important food.

Mandrills have big cheek pouches inside their mouths. They can stuff these with food and carry it somewhere safer before eating it. Big males find most of their food on the ground, while females and young ones search more in the trees.

The IUCN describes a diverse omnivorous diet of fruits, buds, leaves, roots, insects, fish, meat, crustaceans, fungi and seeds; Britannica adds small reptiles and amphibians. Seeds matter more than fruit flesh, and large seeds are usually eaten rather than dispersed.

Mandrills are semi-terrestrial and usually forage less than 5 meters above the ground. San Diego Zoo Wildlife Alliance notes that males forage mostly on the ground for seeds, nuts, fruit and small animals, while females and juveniles feed more in trees, and that large internal cheek pouches let mandrills carry food away to eat in safety.

Mandrills live in very big, noisy groups.

They grunt and scream as they walk through the forest. At night they climb up and sleep in the trees.

Mandrills live in small family groups that join together into enormous groups called hordes, often with several hundred members. One horde in Lopé National Park in Gabon has stayed at about 720 mandrills for 20 years, and one of the biggest groups ever recorded had more than 1,200.

Hordes are noisy. Mandrills keep in touch with deep grunts and high-pitched screams as they travel; the Lopé horde walks about 5 kilometers a day. Adult males join the horde mainly in the breeding season. Each evening mandrills climb into a different tree to sleep.

Mandrills range in hordes of several hundred; at Lopé National Park, the one unhunted horde studied has stayed at about 720 for 20 years, using 182 square kilometers of forest-savanna mosaic and favoring gallery forest and diverse forest fragments. San Diego Zoo Wildlife Alliance cites a group of over 1,200, and hordes in heavily hunted areas are much smaller.

At Lopé, adult males travel with the females and young only in the June to September breeding season and range alone otherwise, covering about 1 kilometer a day against the horde's 4.9. Communication includes grunts, screams, scent marks and body language, and mandrills sleep in trees, choosing a different one each evening.

Mandrills need their forests to stay safe.

Parks in Africa protect places where mandrills live. People work to save their forests from illegal logging and hunting.

The mandrill is vulnerable. People hunt mandrills for meat, and big males are taken most often. Forests are also being cut for logging and farms. Nobody knows exactly how many mandrills there are, because they are hard to count in thick forest.

International agreements protect mandrills, and they live in parks such as Lopé National Park in Gabon, where a large horde is not hunted. Conservation groups work to stop illegal logging and the bushmeat trade.

The IUCN assessed the mandrill as Vulnerable in 2016 (published 2019), suspecting a decline of more than 30 percent over about three generations (24 years). Poaching for meat is the most immediate threat, with large males preferentially targeted and commercial hunters affecting groups near roads and towns; habitat degradation adds to it. Mandrills are most threatened in Cameroon and Equatorial Guinea, and carcasses have been recorded in markets in all four range states.

Total numbers are unknown. The species is listed on CITES Appendix I and is protected in parks and reserves such as Gabon's 4,910-square-kilometer Lopé National Park, but ecologists stress the need for a full census.