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

The migration process is also found in females of other communities studied. For
example, Goodall (1986: 87) gives details of 12 immigrant females, Nishida et al.
(1990: 73–76) give details of 18 immigrant and 13 emigrant females to and from
Mahale M Group, and a further nine females who transferred back and forth (multiple
transfers). Boesch and Boesch-Achermann (2000: 16–17) confirm that the same female
immigration–emigration process happens in the Taï community; indeed, at Taï nearly
every subadult female in the community transfers, which is not the case for the Sonso
community or for Gombe, where some high status females remain in their natal com-
munity for life. In the case of immigrant females, some described by Nishida et al.
(1990) failed to integrate, and this is true of Sonso too; indeed, it may be a failure to inte-
grate that leads to multiple transfers and maybe also to the decision by some females to
emigrate after they have given birth to a new infant, which can lead to infanticide (see
Chapter 7).

Births

Since our study began in 1990 there have been 28 births. Of these, one was premature
and the baby died (in 1997, mother was Kigere), a second was stillborn (in 2002, mother
was Melissa), while three others died in infancy (in 1996, Zip, offspring of Zimba; in
2001, Ben, son of Banura; and in 2002, Monday, son of Mukwano). The annual distri-
bution of the 27 full-term births is shown in Fig. 2.5.
The sample size is not large enough to determine whether there is a birth season at
Sonso. We can compare the Sonso distribution with the distribution of births by month
at other sites. According to Goodall (1986: 108), ‘there is no evidence of a birth season
as such’, but she notes that her sample size (N53) is small; the one for Sonso is even

32 The Sonso community

0

Kwezi Nora,

Helen,

Night,

Monday

Jan Feb Mar Apr May Jun

Months, names of infants (* = died)

Jul Aug Sep Oct Nov Dec

Clint Zed Zalu,

Zig,

Zip*

Rachel,

Kwera's*

Kasigwa Kato,

Kumi,

Keti,

Ben*,

Ramula,

Kuki

Janet,

Kana,

Beti

Rose,

Karo,

Zak

Katia,

Bahati

1

2

3

No. of infants born

4

5

6

7

Fig. 2.5: Distribution of 27 full-term births by month, 1991–2003.