Two of the world’s most endangered primates face extinction as habitats dwindle

In the lush rainforests stretching between Nigeria’s Cross River and Cameroon’s Sanaga River, troops of Preuss’s red colobus monkeys swing through the canopy in groups of 20 to 60 individuals. These social primates depend almost entirely on young leaves from just a handful of tree species for survival, making them extremely vulnerable to forest changes. Their leaf-heavy diet plays a crucial role in shaping forest structure, and scientists consider them an early warning system—when colobus populations decline, it often signals broader ecosystem collapse.

Half a world away on Indonesia’s small Bangka Island, the mysterious Bangka slow loris moves deliberately through the trees under cover of darkness. Distinguished by its pale facial mask and large, reflective eyes, this nocturnal primate is one of the world’s few venomous mammals. Despite being first described in 1937, scientists know remarkably little about this elusive species, though local conservationists have successfully rehabilitated and released dozens of rescued individuals over the past decade.

Both species appear on the “Primates in Peril” list—a sobering inventory of the world’s 25 most endangered primates that serves as an urgent call for targeted conservation action. Their precarious situations highlight a troubling reality: many threatened species depend on incredibly specific conditions for survival. Whether it’s the health of a single island ecosystem, a particular type of forest, or just a few key plant species, the difference between a species’ survival and extinction can hinge on protecting these precise environmental elements. As human activities continue to fragment and destroy these critical habitats, time is running out for both primates.