from the table and, more clearly, from the line graph, the proportion of all Sonso males
represented in parties regardless of size exceeded the proportion of all females.
Sonso females are also sociable, especially if they have infants (as is normally the
case). Bates (2001) made a two-month study of association patterns between Sonso
females, in which she compared lactating females who had young infants with non-
lactating females who had no offspring or whose offspring were independent. There was
little difference in the association patterns of the two groups. Both associated with other
females and adult males and there was no difference in their average party sizes. Bates
found no tendency of lactating females to associate preferentially with other lactating
females and form exclusivenursery groups. Such groups, therefore, when they occur,
probably reflect the numerical frequency of females with infants in the community.
Parties consisting of females and young only, without males, constituted 11.6% of all
parties. Such parties were also described by Reynolds and Reynolds (1965) and Sugiyama
(1968) who called them ‘nursery’ parties or ‘mothers groups’, which is something of
a misnomer as it implies that females without young would be excluded from such groups.
This, as we have just seen from the work of Bates (2001), is not the case; females without
young are found in parties together with mothers and their infants. By contrast, parties
consisting of adult males and infants only were never seen throughout the whole year.^32
By far the commonest party composition at Sonso, as we saw above, was the mixed party.
90 Social organization
(^32) Rarely, males are seen alone with infants, the mother being absent; the consequences may be disastrous
for the infant.
Party size
28.00
25.00
23.00
20.00
18.00
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
Mean % males and females
70
60
50
40
30
20
10
0
% of all in category
Males
Females
Fig. 5.2: Line graph for 482 parties, January–December 2001, showing mean % of all males and
mean % of all females in parties according to party size (range 1–28).