Chimpanzees of the Budongo Forest : Ecology, Behaviour, and Conservation

different tree species and other plant species shed their leaves, and then produce new
leaves, flowers and fruits at different times. Chimpanzees eat the flowers of many tree
species, and flowers contain phytoestrogens which can affect oestradiol action and the
sexual cycle. Other plant compounds such as phenolic acids can inhibit gonadotropin
release, thus blocking ovulation. Further, the action of phytochemicals may not be seen
until three or four months after ingestion. We are a very long way from understanding
how such processes work, but it is possible that they underlie the seasonality of
reproductive and sexual behaviour found at the various sites.

Status

Status is about access to scarce resources. At various points in this book I have referred
to the alpha male of the Sonso community (it used to be Magosi, is currently Duane, and
he will be superceded). The dominant male is supremely confident and relaxed, but he
can be harsh depending on circumstances. He has a glossy coat of hair and a powerful
gait. As we move down the hierarchy males have rather less machismo, then lower still

Status 123

0

Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct

2

4

6

8

10

12

14

16 Gombe

Numbers

0

10

20

30

40

50

60

% Oestrous females

70

80

(^0) Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
1
2
3
4
5
6
7
8 Budongo
Month
Numbers
0
10
20
30
40
50
60
% Oestrous females
70
Males Party size % Oestrous
Fig. 6.5: Seasonality of oestrous females at Gombe and Budongo. Data are aligned with the
graphs beginning at the onset of the wet season. Bars represent mean numbers per month.
Solid lines represent the percentage of females in oestrus (from Wallis 2002a).