Ponso himself was one of 20 chimps abandoned in 1983, but, in the words of one aid group, the island soon became a "veritable massacre." Within months, half of the mistreated animals were dead or missing.
The nine survivors were relocated. A short time after, five more of them were dead.
Ponso was the sole survivor, along with his mate and their two children. But the rest of his little family died within days of each other in 2013. Germain, the villager who had been feeding them, reported that Ponso helped bury his family by throwing dirt on them.
Since then, the elderly chimp - who's at least 40 years old - has been living out his days alone and abandoned on the quiet little island.
"Imagine yourself alone on an island that offers no resources, listening for the least sign or noise that indicates a visitor," SOS PONSO, a group dedicated to saving the lonely chimp, wrote on Facebook. "This is what the sad life of Ponso is reduced to!"