Nut-cracking | Insect-foraging | Algae-scooping | Leaf-folding | Pestle-pounding | Other

Leaf cushion

Bossou chimpanzees were observed to arrange large leaves on the ground as cushions to sit on in order to avoid contact with the wet, moist ground beneath (Hirata et al, 1998).

 

 

Exploratory probing

Chimpanzees at Bossou have been observed to insert sticks or twigs into tree-holes or into the ground and then sniffing the tip upon removal as a form of exploratory behavior.

Leaf clipping

While performing this behavior, a chimpanzee picks one to several soft leaves, grasps the petiole between the thumb and the index finger and then proceeds to repeatedly rip the leaf-blade with its incisors, resulting in the production of a conspicuous and distinct noise.
This behavior is clearly ritualized and serves as a communication signal. The frequencies of mouth to finger leaf clipping vary across chimpanzee communities and leaf clipping has not been observed in all communities of chimpanzees studied thus far. For example, leaf clipping is absent from the behavioral repertoire of the chimpanzees of Gombe. However, it has been recorded at all other long-term study sites across Africa. At Bossou and Mahale (K-group), exclusive use of the mouth for leaf clipping has been recorded, whereas at other long-term field sites, both techniques have been noted with varying frequencies (Whiten et al, 1999).
This behavior has a communicatory function that is usually context-dependent. Indeed, the signaling function of leaf clipping varies across communities. At Bossou, the great majority of examples of leaf clipping is performed to reflect clear frustration or in frustration-related aggression, while only a few instances take place in a courtship context (Sugiyama, 1981). During the habituation period of the Bossou chimpanzees, individuals surprised in trees would leaf clip while watching the observer. Once habituation had progressed, this form of leaf clipping considerably deminished in frequency and is now mainly only seen in youngsters at play.

Aimed Throwing during displays or other aggressive contexts

Chimpanzees at Bossou, as well as at many other study sites across Africa, have been observed to throw a branch at another conspecific during display or fighting contexts or at human observers who happened to come too close!

 

 

Nut-cracking | Insect-foraging | Algae-scooping | Leaf-folding | Pestle-pounding | Other