Walking through the savanna-woodland landscape of Boé National Park, Guinea-Bissau, you might encounter a tree covered in gnarled scars, with an accumulation of rocks surrounding its base.
The chimpanzees may have left the area, but you are lucky nonetheless, because you have stumbled upon evidence of a rare — and potentially cultural — chimpanzee behavior: accumulative stone throwing.
Video recordings show wild western chimpanzees, usually adult males, throwing rocks at specific trees and repeatedly returning to these trees to perform the behavior.
[See video link after end of article.]
While throwing, the chimpanzees pant hoot — a loud, long-distance communicative signal — and sometimes repeatedly hit their hands and feet on the tree in a behavior called buttress drumming.
