Parties were analysed to see to what extent they consisted of one sex only or of both
sexes. Only parties consisting of adults and subadults were included in order to exclude
the effects of kinship bonds on juveniles and infants. When parties consisted of one sex
only, there were more all-male parties than all-female ones (42 (8.7%) all-male and 15
(3.1%) all-female). All-male parties were larger than all-female ones; all-male parties
numbered from 1 to 8 individuals with a mean of 2.44, whereas all-female parties num-
bered from 1 to 2 with a mean of 1.06. By contrast, there were 355 (73.65%) parties
consisting of both sexes: such mixed parties numbered from 2 to 28 (excluding infants)
with a mean of 10.22. Mixed parties are thus the norm at Sonso and constitute the
great majority of parties seen.
Much has been written about the tendency for female chimpanzees to be more individ-
ualistic and less gregarious than males (see, for example, Wrangham 1979, 2000a;
Nishida 1990; Pepper et al. 1999; Emery Thompson and Wrangham, in press). In
order to take account of the different proportions of males and females in the community,
numbers of adultssubadults of each sex were converted into percentages of the total in
each of these two age classes in the community (see Emery Thompson and Wrangham, in
press). The results for both sexes are shown in Table 5.1 and in Fig. 5.2. As can be seen
Party composition 89Table 5.1: Statistics for 482 parties, January–December 2001,
showing mean % of males and mean % of females in parties
according to party size (range 1–28).
Party size Males (%) Females (%)
1.00 3.02 2.24
2.00 4.77 3.55
3.00 8.95 4.09
4.00 8.84 7.24
5.00 12.16 8.51
6.00 16.52 8.57
7.00 20.26 11.21
8.00 20.91 13.97
9.00 29.78 12.50
10.00 33.63 13.57
11.00 35.42 15.00
12.00 35.71 18.33
13.00 36.31 19.76
14.00 43.75 19.44
15.00 46.87 20.00
16.00 50.42 22.67
17.00 40.18 30.71
18.00 47.73 28.18
19.00 57.81 26.25
20.00 50.00 34.00
22.00 54.17 36.67
23.00 53.12 37.50
24.00 50.00 40.00
25.00 62.50 40.00
26.00 62.50 45.00
28.00 62.50 55.00
Mean 24.02 12.65