The Preuss’s monkey is classified as Endangered by the International Union for Conservation of Nature (IUCN, 2018), appearing on the IUCN Red List of Threatened Species.

Primates around the world are threatened by human activities that destroy their natural habitats, and the situation for Preuss’s monkeys is no different. Logging and agricultural practices in Cameroon and Nigeria have had adverse effects on these mainland populations. Though most of these monkeys live at higher altitudes where crops are virtually ungrowable, much of the once-intact highland forests they call home has been converted into grazing land for cattle.

Coffee is one of Cameroon’s biggest exports, and its cultivation has played a key role in the country’s deforestation as well. In the 1980s and 1990s, the rise in the price of coffee around the world initiated rapid clearing of their forests. Even after coffee prices fell again, farmers hopeful for another price spike meant that these practices continued unabated. As a result, the scant amounts of montane forests that would be prime habitat for Preuss’s monkeys now exist mostly in separate and small patches.

Forest loss in Cameroon was higher in 2014 than all previously recorded years, and still shows no signs of waning. Until they are properly protected, it is only a matter of time before these few refuges are also destroyed by human activities.

Preuss’s monkeys are also greatly threatened by bushmeat hunting. As a semi-terrestrial and relatively large-bodied species, they are particularly susceptible to human predation. For a long time, the remoteness of their habitats kept them relatively protected. However, as forests have diminished and new roads have been built, these natural defenses have proven less effective.

Though hunting is a threat to both subspecies, the situation has become particularly bad for the Preuss’s monkeys on Bioko Island. Even in the island’s protected areas around Pico Basilé and the Gran Caldera Scientific Reserve, hunting has increased in the last twenty years as new roads being built have given hunters easier access to their once-remote habitats.

In spite of easier access to their habitats, researchers still struggle to find populations of Preuss’s monkeys in the wild. Surveys of regions where this species was once considered common have sometimes turned up zero sightings. Such findings paint a bleak picture for this species. So much remains unknown about this shy and elusive species that the inability to do research on them presents its own kind of threat. Unless researchers are able to start filling in the blanks soon, the measures that best serve their conservation may never become known.