While most wildlife enthusiasts are already familiar with chimpanzees and gorillas, a West Africa cruise along The Gambia allows visitors to become acquainted with a more unique type of primate — red colobus monkeys.

Red colobus monkeys thrive in the country's Abuko Nature Reserve alongside callithrix monkey and nearly 300 species of birds. Deriving their name from the Greek word for "docked," red colobus monkeys have just a bump in the place their thumb should be. Other phalanges are particularly long, however, allowing the primates to swiftly move through the forest canopy in search of leaves, shoots, fruits and fungi that make up its diet.

This subspecies is currently listed as Critically Endangered by IUCN (the International Union for Conservation of Nature), because of common, though illegal, hunting and loss of habitat. However, humans are not the only ones threatening the monkeys' existence. According to a recent study, chimpanzees in Uganda have been found to overhunt red colobus monkeys, hurting their numbers significantly.

According to New Scientist, this hunting has caused the local population of the red colobus monkeys to fall to one tenth of what it was 33 years ago. Although the numbers have not been determined in The Gambia or at the reserve, the study shows the first time that a non-human primate has been found to overhunt another, leading to population decline.

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