The vivid coloration of their bottom is a result of blood vessels located there



The vivid coloration of their bottom is a result of blood vessels located there

Population 4,000
70% population decline in the past 30 years

Sporting a dark grey-brown coat and a short tail, drills present a striking appearance that is further enhanced by the vibrant hues adorning their rumps, which range from shades of pink and mauve to hints of blue. These colors serve as visual cues within the social dynamics of drill communities, allowing individuals to convey emotions and assert dominance through facial expressions and body language.

One of the most notable characteristics of drills is their sexual dimorphism, with males exhibiting significantly larger sizes and distinct physical features compared to females. Male drills boast a pink lower lip, a distinguishing trait absent in females, adding a splash of color to their already captivating appearance. This disparity in size and coloration plays a crucial role in mating rituals and social hierarchies within drill groups, influencing mating preferences and territorial disputes.

Facial expressions are a primary means of communication among drills, with individuals often using subtle gestures such as exposing their teeth and adopting a “grin-like” expression to convey their intentions and emotions. While such displays are typically friendly in nature, drills may also employ them during conflicts or confrontations, signaling dominance or aggression within the group dynamic.

Despite their remarkable adaptability and resilience, drills face numerous threats to their survival, primarily driven by human activities. Illegal habitat destruction, commercial hunting for bushmeat, and rampant human development have led to a sharp decline in drill populations over the decades, pushing them perilously close to extinction. Hunters, motivated by profit and demand for exotic meats, pose a significant threat to drill populations, with expeditions resulting in the indiscriminate killing of up to 20 drills at a time.


Population est.
Equatorial Guinea

Did you know?

  • Drills are only found in Nigeria, SW Cameroon, and the island of Bioko; they were thought to be extinct in Nigeria and on Bioko island in the 1980s.
  • An oddly positioned crimson red line under their lower lip looks like misplaced lipstick.
  • Males with the brightest rumps have the highest rank! Their colorful rumps are said to be an indication of rank.
  • In contrast to other monkeys that only exhibit their “appeasement grin” in angry situations, drills utilize it mostly for greeting.
  • Drills walk on their hands and feet’s flat surfaces rather than their knuckles like apes do.
  • The drill monkey is one of the world’s least-known primates due to its low numbers and the difficulty of studying them in their small remote range habitat.
  • According to census estimates, there are just a few thousand drill monkeys left in the wild. Over the last 30 years, continuous threats have reduced the population by more than 50%-70%.
  • Drills are among Africa’s most endangered mammals, and the IUCN declared them to be the most endangered of all African primates.
  • Drills are very vocal, which allows groups to remain cohesive. They produce a lot of noise in the forest, which makes them an easy target for hunters.
  • As part of a conservation effort, an in-situ facility in Nigeria maintains a large, genetically diverse population; another captive population is kept in Cameroon.

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Terrestrial / Aquatic

Altricial / Precocial

Polygamous / Monogamous

Dimorphic (size) / Monomorphic

Active: Diurnal / Nocturnal

Social behavior: Solitary / Pack / Herd / Troop

Diet: Carnivore / Herbivore / Omnivore / Piscivorous / Insectivore

Migratory: Yes / No

Domesticated: Yes / No

Dangerous: Yes / No