Fotos © Cyril Ruoso

The Drill

Drills (Mandrillus leucophaeus) are among Africa’s most endangered mammals, and are listed by the IUCN as the highest conservation priority of all African primates. Drills are only to be found in Cross River State in Nigeria, Southwest Cameroon and on the Island of Bioko. Their entire world range is less than 30,000km², an area smaller than Switzerland.

They are semi-terrestrial monkeys, exhibiting extreme sexual dimorphism with males weighing up to 35kg - three times that of a female. They are semi- nomadic seasonally and very little is known about their behaviour or ecology in the wild who spends most of his life as a nomad foraging in little or non explored rainforest.

Drills live in groups of up to 30 members consisting of several adult males, sub adults, as well as females and juveniles.

The next living relative is the Mandrill (Mandrillus sphinx). Both belong to the genus Papio, subgenus Mandrillus.

©Cyril Ruoso

Life expectation is 25 years for the males where females can average 35 years old or more.

Young females reach sexual maturity at the age of five, Juvenile males with eight, dominate adult males advance to becoming alpha male at average of 10 years of age. During this time they take on the typical blue-violet buttock colouring and further more the red lower lip, distinctive dark nose contours, and the white corona surrounding his face.

His impressive canines can reach a length of 10cm and are formed in a pointed backwards angle, this enables the adult males to attack and defend against leopards, the only other natural enemy or threat in their rainforest habitat with the exception of birds of prey hunting juveniles.

The typical female attribute as of many primates is the monthly swelling of the sexual organ indicating readiness for copulation.

After approximately 190 days gestation, they give birth to a single young.

©Cyril Ruoso

After two to three years the female is in condition for the next birth, since her previous young now should be weaned and independent enough, the first year the young drills require lactation but are also capable of taking solid foods, later fruits, vegetables, roots, and seeds become there major food source of nourishment, but also small vertebrates and insects are a welcome variety to their diet.

The population of these shy forest living dwellers is continually endangered through illegal poaching, hunting, eroding, and in recent times establishment of new settlements, also the demand for monkey meat - otherwise known as “bushmeat” is increasing due to hunters who without any scruples sell their “kills” in the townships. through industrial logging and felling of the tropical rainforest large areas are being eroded and destroyed forever, these shy forest dwellers are constantly on the move searching for protected forest with intact structures for them to survive, these Forest areas are continuously under pressure through the wood industry building access roads, these roads mean that there less opportunities to mix with other groups, thus the long term problem is of “in breeding” due to lack of Genetic exchange.

In the late seventies the drill was considered to be extinct in Nigeria.