5. Social organization
7.30 Into forest with Zephyr. 7.45 KewayaKatia. Nick on trail ahead. Tinka. Mukwano in oestrus 4.
JanieJanet. Nkojo with erection as Mukwano approaches up the tree. Kwera in oestrus 4Kwezi.
Maani present. Fine adult male. Zefa displays & mates with Kwera who dashes off at the end of it.
Bwoba. We are in block 4C. Feeding on Cya seeds (Cya is late this yr as the dry season was a month
delayed and lasted till early March). 8.26 Kwera cop with Nkojo. Gashom. Duane descends tree force-
fully. Black. Order of march along trail: Duane, Black, Nkojo, Maani, Zephyr (human), me. They stop
to feed on Chrysophyllum albidumfruits (large fleshy yellow plum-sized fruits). NB Gashom has snare
(new) right hand. 2 fingers tightly held together by the wire (17 March 2001).In this chapter we shall be concerned with the principles of social organization of the
Sonso community, that is to say the way the community itself is organized. In the next
chapter we shall move on to the social behaviour of the chimpanzees themselves.
The whole group that lives in a range or territory (within which it splits up into
subgoups) is called a ‘community’ (or especially in Japanese primatology, a ‘unit
group’, e.g. Nishida 1968, 1990) and the temporary subgroups into which the commun-
ity divides are called ‘parties’ (for a review of terminological issues see Van Elsacker
and Verheyen 1995). How and why parties form and split up, re-form and split up again,
is a subject that we shall approach in this chapter.
The problem of how to define parties remains a difficult one because of their temporary
nature. Boesch (1996) points out that for different observers a party may consist of all
individuals in sight of one another, or all individuals in auditory contact, or all individuals
within a certain distance of each other. No fixed cut-off distance was used in the present
study; the individuals were not always in the same tree but could be in adjoining trees or
some might be on the ground and others in the trees above. The decision to include
individuals in a party was in the last analysis subjective, and efforts to find an objective
method have so far proved problematic; perhaps a reasonable working definition might be
‘all the individuals that appeared to be aware of each other’s presence’ (R. Wrangham, pers.
comm.). Some observers, e.g. Newton-Fisher, have used a 30 m diameter cut-off point for
party size and this is useful for some purposes. Chapman et al. (1993) point out that
quantifying subgroup size is made difficult by limited visibility, extent of habituation and
observation methods. These factors are important in making comparisons between one
study and another. However, where studies are long term it seems possible to attempt a few
comparisons, especially where conditions of observation are similar.