by females: at Gombe (Goodall 1986), at Mahale (Nishida 1989) and at Kibale
(Wranghamet al. 1992). De Waal (1982) described the female dominance hierarchy as
being more influenced by subordinacy (via pant-grunts) than by dominance (via aggres-
sion). Pusey et al. (1997), analysing 35 years of data from Gombe, found that high
ranking females had higher infant survival and shorter birth intervals than low ranking
females. The reason, they suggest, is that high rank gives females improved access to
areas of high food quality. As suggested in Chapter 2, food may be more of a limiting
factor at Gombe than at Budongo. For example, the same authors found that immigrant
females are sometimes attacked by resident females, even coalitions of resident females;
this has occasionally been seen at Sonso, where immigrant females are sometimes bold
and integrate well as soon as they arrive, but at other times are shy and evasive and may
be attacked by resident females. For example, a prolonged attack was observed on the
immigrant Juliet, a subadult nulliparous female, by Nambi and Ruhara during January
2003 (the aggression lasted 15 min on 29 January). At Mahale the situation is similar:
Nishida (1989) found that younger, nulliparous and recently arrived females tended to
pant-grunt to older, multi-parous and longer resident females indicating some degree of
fear of them.
Female association patterns at Sonso, and status among the Sonso females, have been
studied by Fawcett (2000). The main behaviours she used to record dominance were
aggression, chasing, displacing and pant-grunting. She recorded 102 dominance inter-
actions between females. Although it would be risky to claim there was a hierarchy on
the basis of this sample size, interactions between the same pair of females always went
the same way. The alpha female was Nambi (NB), who was dominant over the largest
number of females. Two other females, Kwera (KW) and Kewaya (KY), were second
and third in dominance over other females; as related earlier these two females were
very close associates as adolescents and had their first oestrous periods at the same time.
A recently immigrated female, Clea (CL), was subordinate to the largest number of
females and did not dominate any other female. Thus one factor emerging out of the
Budongo data (as elsewhere) is that long residency is linked to high status. By the same
token, Fawcett found that three immigrant females, Emma (EM), Mama (MM) and
Harriet (HT), were more loosely associated with the community than females who had
been resident for longer.
Five pairs of females did have close relationships,^57 echoing the situation at Taï. There
was also some evidence of female alliances, albeit short-lived ones, e.g. when Zimba
and Kewaya jointly chased away an unidentified immigrant female, and when Ruhara
and Sara formed a temporary alliance to stop Kalema entering a feeding tree; the first of
these pairs is a mother–offspring pair^58 so that kinship is involved. Kewaya had two
close associates. Nambi, the alpha female, had a close associate, Kutu, a lower ranking
female.
132 Social behaviour and relationships
(^57) Closeness was measured by having significantly higher than the mean dyadic association index between
females. 58
This was indicated by behavioural data and has subsequently been confirmed by genetic analysis.