The forests of Sapo hold significant populations of western chimpanzees and other primates — Diana monkeys, red colobus, sooty mangabeys, putty-nosed monkeys among them. Researchers from the Wild Chimpanzee Foundation, SCNL and international universities have run long-term monitoring at several sites within and around the park, mostly using camera-trap arrays and nest surveys.
For visitors, the practical takeaway is that chimpanzees are present but rarely seen directly — they are unhabituated to human presence and will move away from the sound of a trekking group. What you will much more often hear are pant-hoot calls drifting across the forest at dawn, and you will find nests, knuckle prints and other sign. The other primates are more often glimpsed in the canopy, especially the Diana monkey.