distribution of numbers of oestrous females in parties is shown in Table 5.2. One or
more oestrous females was present in 244 of the 483 parties seen. The percentage of
males present in these parties is shown in Fig. 5.3.
As can be seen, the mean and absolute percentage of males rose as more females
entered the party. In the few cases where 4 or 5 oestrous females were present (two cases
each) we can discount the results because of the small sample size. The overall impact
of oestrous females on males is very marked, with an increase from 25% to 45% of all
males present as the number of oestrous females increases from 1 to 3. A correlation of
these two variables gives r0.332, with p0.01.^34
92 Social organization
Table 5.2: Number of oestrous females present in
483 parties (data for January–December 2001).
No. of oestrous No. of parties Per cent of parties
females
0 239 49.5
1 139 28.8
2 77 15.9
3 24 5.0
4 2 0.4
5 2 0.4
Total 483 100.0(^34) The effect of food abundance has not been analysed for the above data; it may be that part of the increase
in the number of males in this data set was due not to the presence of oestrous females but to the presence of
plentiful food. The influence of food supply on party size is considered in more detail below. However,
increased presence of adult males in parties with oestrous females is likely to be independent of food supply
because such females act in their own right as a magnet for males.
Fig. 5.3: Boxplot showing percentage of males in community in parties without and with oestrous
females.
No. of parties 239 139 77 24 2 2
1 2 3 4 5
Per cent of all males present
70
60
50
40
30
20
10
0
–10
No. of oestrous females 0