Happy MAD MAMMAL MONDAY! Today’s mysterious mammal is the doughty drill (Mandrillus leucophaeusdrill)!

Drills are endemic to Cameroon, north of the Sanaga River, the south-eastern part of Nigeria, and the coastal island of Bioko, and are among Africa’s most endangered primates. They are closely related to mandrills, and less so to baboons.

These semi-terrestrial species can be found in lowland forests, coastal, and riverine forests. 

Ranging between 60 and 76 cm in length, male drills can weigh up to 25 kg, while females weigh less than half at only 11.5 kg. They have olive brown fur, short tails, jet black faces with bright red lower lips, and have prominent ridges on the side of their nasal bones. This genus is distinguished by beards, manes and crests. They have bright red rumps which are less prominent in females and juveniles, and the genitals of males are lilac or violet.

Drills are omnivorous and feed mainly on fruit, leaves and invertebrates.

Communication occurs predominantly through visual displays of the brightly coloured posteriors, although tactile communication is also important. Drills are very noisy, regularly screaming and grunting, but the reason for this is still unknown.

M. leucophaeusdrill is listed as Endangered on the IUCN Red List of Threatened Species, and is greatly threatened by habitat loss and excessive hunting – drills form huge aggregations, often resulting in mass slaughtering of up to 20 individuals in one shooting.

The Drill Project features the first-ever broadcast images of wild Bioko Island drills and tells a tale about their biology.”

Remember to submit your mammal records via our virtual museum or through our blog.


Oates, J.F. & Butynski, T.M. 2008. Mandrillus leucophaeus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <>. Downloaded on 13 January 2014.

Briercheck, K. 1999. Mandrillus leucophaeus. In: Animal Diversity Web. <>. Downloaded on 13 January 2014.

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