and others^45 who have looked into this carefully. We were finding and naming new adult
females until 1996 (Harriet was the last), after which there were no new adultfemales
found until the three who arrived in 2001. Added to this, recognition of the new females
was made easy by the fact that both Wilma and Flora were missing hands, while Melissa
was quickly and easily identified by her resemblance to the adult male Jambo.
Interestingly also, none of the new females, neither the more habituated ones who were
not scared of observers, Melissa, Wilma and Sabrina, nor the more skittish ones who
seemed to be less habituated, Flora, Polly and Juliet, moved around on the periphery of
the Sonso range; they were first seen near the middle of the range. This is in contrast
with the situation in Gombe and Kibale where only the most well-established females
occupy the middle of the range. As regards the behaviour of our adult male residents,
Sabrina’s first oestrus in October 2001 caused great excitement among our males; the
swellings of the other females caused no more than normal levels of excitement; and no
aggression against the incoming females was seen, either from the adult males or the
resident adult females.
One of the recent immigrant females, Sabrina, with her daughter Sally, did not imme-
diately settle in Sonso, but disappeared after 10 months, in August 2002, and was seen
only twice during the following year, after which she returned. These movement
patterns by females are not normal either in Sonso or in other communities such as
Taï (Boesch and Boesch-Achermann 2000), Mahale (Nishida 1990) or Kanyawara
(R. Wrangham, pers. comm.)
At other sites, notably Gombe and Mahale, adult females have joined a new commun-
ity when the adult males of their own community were attacked by males from the new
one. We obtained no evidence of such attacks at the time these females appeared.
Having considered various options, those who observed these events have concluded
that this influx of females and young may have been the outcome of the disintegration
of a neighbouring community, perhaps as a result of human activity such as intensive
pitsawing, or for other reasons.^46
Inter-community fighting
The first report of inter-community fighting in chimpanzees came from Goodall’s Gombe
studies (Goodall 1986). Over a period of several years, males of the Kasakela community
killed males of the breakaway Kahama community and took over the Kahama territory
and the Kahama females. In similar fashion, at Mahale, prolonged conflict between the
K and the M communities appears to have been responsible for the annihilation of the
K community, its males were probably killed and its females moved to join the M
community. Both the above were in Tanzania. In Uganda inter-community conflict has
106 Social organization
(^45) Besides Melissa Emery Thompson, Sean and Catherine O’Hara and Lucy Bates have, with me, explored
this possibility thoroughly in the course of numerous exchanges.
(^46) I am grateful to Lucy Bates, Melissa Emery Thompson, and Sean and Catherine O’Hara for providing
relevant data and for lengthy discussions about this issue. The idea that the females came from a disintegrat-
ing community was Melissa Emery Thompson’s and was subsequently accepted by the group.