at Bossou customarily dip for ants using wands (Sugiyama et al, 1988;
Sugiyama, 1995). The most common prey species is the driver or army
ant, genus Dorylus (Anomma). Five species of Dorylus ants (D. emeryi
(Mayr), D. gerstaeckeri (Emery), D. mayri (Santschi), D. arcens (Westwood)
and D. nigricans (Illiger)) have thus far been identified at Bossou
by Dr. Caspar Schöning. D. molestus, which had previously been
noted as present at Bossou by Sugiyama et al (1988), was, however, not
identified in the recent samples collected from Bossou. Army ants construct
underground nests that are not easily noticeable, unless ants are scrambling
at the surface. However, since they use these nests as temporary bivouacs,
they also move around in large columns on the ground when migrating
or foraging. They can travel in great numbers on the surface of the
ground and amongst terrestrial herbaceous vegetation hunting for prey,
e.g. earth worms. Ants' nests are usually dug up by hand. Chimpanzees
at Bossou have also been observed to dip on ant trails on the forest
floor. Bossou chimpanzees typically hold the wand between their index
and their middle fingers and perform a back and forth movement of the
wand so as to stimulate the ants to attack of the intruding object.
Ants that climb up the wand are typically directly mouthed by wiping
the tool through the lips or teeth, a technique known as "direct
mouthing". But chimpanzees at Bossou also employ another technique,
termed the "pull through" technique, i.e. swift and meticulous
swiping of the length of the tool from the proximal to the distal end
with the hand and ingesting the gathered bundle of ants from the collecting
hand. Environmental influences on wand length and technique employed
during ant dipping have been uncovered in the Bossou community (Humle
and Matsuzawa, 2002).
Other species of ants consumed by Bossou chimpanzees include the weaver ant (Oecophylla longinoda). Although these are usually eaten directly by hand, Sugiyama also reported the use of a tool in fishing these ants (Sugiyama, 1995).
More recently, Yamamoto and colleagues also observed Bossou chimpanzees fishing for arboreal species of ants (Camponotus sp.)(Yamamoto et al. 2008).
Up until 1997, no cases of termite fishing using a twig to fish for termites (Macrotermes sp.) were ever observed at Bossou, although Macrotermes mounds are common within the home range of the chimpanzees. In 1997, during the end of the rainy season, an adult female, Yo, and her juvenile offspring, Yolo, aged six at the time, were observed using a short flexible stalk of a terrestrial herbaceous plant to fish for Macrotermes termites (Humle, 1999).