Are there really freshwater manatees thriving deep within West Africa?

“THIS is a perfect place for manatees,” says Lucy Keith-Diagne, squinting at a slow, muddy sweep of the Niandan river. It seems improbable: why would these lumbering aquatic mammals, also called sea cows, be living some 4000 kilometres up the Niger river in Guinea, almost as close to the Sahara desert as to the Atlantic Ocean? But as the world expert on African manatees, Keith-Diagne would know.

These chubby creatures are known to reside lower down the Niger river, which stretches like a giant boomerang through much of West Africa, and anecdotal evidence over the years has hinted at another population high up in tributaries near its source. What’s more, Keith-Diagne believes this group has been separated from other manatees for so long that its members could be evolving into a separate subspecies. “They went up the Niger. They found good stuff. They kept going. They never came back and they became different,” she says. But, for now, this is just a guess.

To find out more, we have driven hundreds of kilometres from Guinea’s swampy coast, over the highlands and down into the forested savannah in search of these elusive creatures. In a two-week expedition, Keith-Diagne and her team will interview locals, chase up any leads on recent sightings and look for telltale signs of feeding along riverbanks. Crucially, they will also collect samples of…