KINGDOM: Animalia (Animals)
PHYLUM: Chordata (Possessing a notochord)
CLASS: Mammalia (Mammals)
FAMILY: Cercopithecidae (Old World Monkeys)
SUB-FAMILY: Cercopithecinae (Monkeys incl. Baboons, macaques and vervets)
GENUS: Mandrillus (Mandrill and Drill)
SPECIES: Mandrillus leucophaeus (Drill)
Drills are endemic to North Africa. They are only found in Nigeria, Cameroon and the island of Bioko(in Equatorial Guinea) in the equatorial rain forests. The drill is one of the most endangered of all African primates.
Drills are similar in appearance to their cousins, the mandrills, however, they lack the bright facial coloring of mandrills. Their body fur is an olive-brown colour, with the underside being a white-grey colour. The face and ears are black, with distinct ridges on the side of their nasal bones. The rump is pink, mauve and blue. Males can be easily distinguished from females by their pink lower lip. Males are also almost twice the size of females, and usually weigh about 25kg, with females only weighing about 11.5kg on average.
Drills inhabit lowland, submontane rainforests. Drills are quadrupedal and forage on the rainforest floor. Although they are very good climbers, they mostly only climb trees to sleep in.
Drills are mainly frugivores (fruit eaters) but are sometimes considered omnivores, because they will also eat termites, plants, dry food, sea turtle eggs, crabs, snails and even vegetables.
They are semi-nomadic and will form mixed sex groups, generally consisting of about 20-30 individuals, typically led by a dominant male. These small groups come together with other groups to form supergroups of up to 200 individuals. Because of the nature of their habitat, drills have not been studied extensively and so their social organization and group size dynamics are unfortunately still poorly understood. It is likely that drills are polygynous (males will have more than one female mate at a time), however, their breeding habits have not been studied extensively.
Drills have various communication methods, including olfactory (smell), tactile (touch), visual and vocal communication. Scent glands on their chests are used to mark their territory. Furthermore, like most primates, grooming is very important to drills, acting as a social bonding tool. Touch is also a very important behaviour between parents and babies as well as mates. Visual communication is the main communication method for drills, and they use various signals such as head jerks, lip smacks, tension yawning and smiling. But, drills are also noisy primates, emiting a range of grunts, barks and squeals, the meaning of which is mostly still unknown.
The dominant male will father most of the offspring in the group. Gestation is between 179-182 days and females typically give birth to a single offspring (although twins have been documented). At 15-16 months young drills are weaned and will leave their mothers. Females become sexually mature at about 3 years of age, and males at about 6 years. Males will usually disperse from their home groups to form new groups. They can live to about 30 years.
Drills are preyed on by leopards, crowned eagles, snakes and humans.
The main threats faced by drills are habitat loss due to the construction of roads and the bushmeat trade. They are also sometimes seen as pests and are shot by farmers.
Did you know?
- Drills only have a stub of a tail
- They use facial expressions. The grin is actually a friendly gesture and not a threat!
- Fewer than 10,000 drills remain in the wild, and numbers may be as low as 4,000