This week’s Animal of the Week is the Mandrill, one of the most colorful and recognizable primates in the world.
Mandrills (Mandrillus sphinx) are large Old World monkeys found in the tropical forests of Central Africa. Adult males are especially striking, with brilliant red noses, blue or purple facial ridges, golden facial hair and brightly colored skin on the rump.
Although mandrills are sometimes called “forest baboons,” they are not true baboons. They belong to the genus Mandrillus, along with their closest living relative, the drill.
Mandrills also hold an impressive title: adult males are the largest living monkeys in the world.
Quick Facts
Animal: Mandrill
Scientific Name: Mandrillus sphinx
Animal Type: Mammal — Primate
Family: Cercopithecidae
Diet: Omnivore
Body Support: Endoskeleton
Group Name: Horde or troop
Newborn Weight: About 1 to 2 pounds
Average Size: About 24 to 30 inches in body length; adult males may reach around 32 inches in height
Average Female Weight: About 25 pounds
Average Male Weight: About 55 pounds, although exceptionally large males may weigh considerably more
Average Lifespan: About 20 years median life expectancy in managed care; some individuals can live more than 30 years
Top Speed: No scientifically established maximum running speed is currently available
Habitat: Tropical rainforests, montane forests, secondary forests and dense bush
Range: Southwestern Cameroon, Equatorial Guinea, Gabon and southwestern Republic of the Congo
Conservation Status: Vulnerable
Mating Season: Mating commonly occurs from about July through October, although breeding can vary with food availability
Babies: Usually 1 infant; twins are uncommon
Social Life: Highly social; smaller groups may combine into enormous hordes containing hundreds of mandrills
What Makes Them Special
Mandrills are famous for their extraordinary coloration.
Adult males have:
- A bright red stripe running down the center of the muzzle
- Blue or purple ridges on both sides of the nose
- Red lips
- Golden or yellow facial hair
- Brightly colored skin on the rump
- Large canine teeth
Females and young mandrills are much less brightly colored.
A male’s coloration can also provide information about his condition and social status. Higher-ranking males often develop stronger coloration, while males that lose status may become less intensely colored.
Mandrills also show extreme sexual dimorphism, meaning males and females differ greatly in appearance and size.
Adult males can weigh roughly twice as much as females and develop much larger canine teeth.
Habitat
Mandrills live in the tropical forests of equatorial Central Africa.
Their range includes:
- Southwestern Cameroon
- Equatorial Guinea
- Gabon
- Southwestern Republic of the Congo
They can live in:
- Tropical rainforest
- Montane forest
- Secondary forest
- Dense bush
Mandrills spend much of their daytime activity on the forest floor, where they travel and search for food.
Despite being primarily terrestrial during the day, they are excellent climbers.
At night, mandrills climb into trees to sleep and may choose a different sleeping tree each evening.
Diet
Mandrills are omnivores with a highly varied diet.
They may eat:
- Fruits
- Seeds
- Nuts
- Roots
- Leaves
- Fungi
- Insects
- Snails
- Worms
- Frogs
- Lizards
- Snakes
- Other small vertebrates
Fruit is an especially important part of their diet when it is available.
Mandrills also have large cheek pouches that allow them to quickly collect food and temporarily store it inside their mouths. They can then move somewhere safer before stopping to eat.
Adult males often forage on the ground, while females and younger mandrills may spend more time searching for food in trees.
Behavior
Mandrills are primarily diurnal, meaning they are active during daylight hours.
During the day they spend time:
- Traveling through the forest
- Searching for food
- Feeding
- Resting
- Grooming
- Communicating with other mandrills
Dense rainforest vegetation can make it difficult for members of a group to see one another, so communication is extremely important.
Mandrills communicate through:
- Deep grunts
- Screams and other vocalizations
- Facial expressions
- Body posture
- Touch
- Grooming
- Scent marking
Male mandrills have a scent gland on the chest that they may rub against objects to leave chemical signals.
Mandrill facial expressions can sometimes be misunderstood by humans. Showing their large canine teeth does not always mean aggression. Certain relaxed tooth-baring expressions may actually signal friendliness or submission.
Social Life
Mandrills are highly social primates.
Females and their offspring form the stable core of mandrill society.
Smaller social groups may temporarily join together to form enormous gatherings known as hordes.
One documented mandrill gathering contained more than 1,200 individuals.
Within these groups:
- Females often remain within their social network
- Young animals interact and play with one another
- Grooming strengthens relationships
- Social rank influences access to mates and resources
- Adult males may spend periods away from the main female-centered group
Mandrills use vocalizations, scent, body language and grooming to maintain relationships within these complex societies.
Mating
Mandrills have a polygynous mating system, meaning a successful male may mate with multiple females.
Mating commonly occurs from approximately July through October, although reproduction can vary depending on food availability and environmental conditions.
During the breeding period:
- Dominant males compete for reproductive opportunities
- Females can choose which males they associate with
- Higher-ranking males often have more mating opportunities
- Bright male coloration may signal reproductive condition and status
Pregnancy lasts approximately six months.
San Diego Zoo Wildlife Alliance reports a gestation period of approximately 179 to 182 days.
Females generally produce one infant rather than a large number of offspring at once.
Babies
A baby mandrill is called an infant.
Females normally give birth to:
- 1 infant at a time
- Twins only occasionally
Newborn mandrills weigh about 1 to 2 pounds.
Infants are born with:
- Dark fur
- A pinkish face
- A dark cap of hair
- Lighter hair on portions of their arms and legs
- Open eyes
Soon after birth, the infant can cling tightly to its mother’s body as she moves through the forest.
The mother provides most of the baby’s care, including:
- Milk
- Protection
- Transportation
- Grooming
- Warmth
Other females and relatives may also interact with young mandrills by carrying, grooming or playing with them.
Young mandrills remain closely associated with their mothers while gradually learning how to find food, communicate and function within the group.
Conservation Status
Mandrills are classified as Vulnerable.
Major threats include:
- Habitat destruction
- Logging
- Agricultural expansion
- Forest clearing
- Growing human settlements
- Hunting for bushmeat
Large social groups can make mandrills especially vulnerable to hunting because many individuals may be concentrated within the same area.
Protecting large connected areas of Central African rainforest is critical to maintaining healthy wild mandrill populations.
Conserving their habitat also protects countless other species that depend on the same forests.
How You Can Help
People can help mandrills by:
- Supporting organizations that protect Central African rainforests
- Choosing responsibly sourced wood and paper products
- Supporting efforts to reduce illegal wildlife hunting
- Avoiding wildlife products connected to the bushmeat trade
- Supporting reputable wildlife conservation programs
- Sharing accurate information about mandrills and rainforest conservation
Protecting mandrills ultimately means protecting the forests they depend on.
Final Fun Fact
Fun Fact: quickly gather food, store it inside their cheeks and carry it somewhere safer before stopping to eat.
Sources
San Diego Zoo Wildlife Alliance — Mandrill
Mandrill | San Diego Zoo Animals & Plants
Animal Diversity Web — Mandrillus sphinx
Mandrillus sphinx (mandrill) | INFORMATION | Animal Diversity Web
IUCN Red List of Threatened Species
IUCN Red List of Threatened Species