The dynamics of social relationships among female Chacma baboons (Papio cynocephalus ursinus) in Zululand.
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Date
1993
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Abstract
The focus of this study is the effect of environmental
conditions on the social relationships among females in a
free-ranging troop of chacma baboons (Papio cynocephalus
ursinus), in a southern woodland habitat. The female
dominance hierarchy, rank related differential costs and
benefits to individuals, and the nature of special
relationships between females, were followed. The study was
conducted for a total of 18 months during three years, at
Mkuzi Game Reserve, Zululand, South-Africa. The study troop
occupy a rich woodland habitat with abundant food
resources. Visibility under these conditions is poor and
the baboons are subjected to leopard predation. Intra-troop
competition for food among female primates and its effect
on lifetime reproductive success, has been widely stressed
to be a major cost for low ranking females. No evidence of
competition for food was found among females at Mkuzi. It
is suggested that the main cause for mortality may be
predation by leopards, and that females compete mainly over
a safe spatial position. The following characteristics of
female sociality at Mkuzi may support this suggestion:
1. While no indication of rank related feeding
behaviour, reproductive success, or 'attractiveness' to
others was found, the higher ranking females had more
access to central, and thus better protected, spatial positions in the troop.
2. The importance of social associations among females
at Mkuzi seems to lie in mutual grooming and protection
from predation by the vicinity to each other, and not in
coalitionary support. Female associates were thus not
necessarily adjacent ranking and probably not kin.
3. Although female dominance hierarchy was usually
stable, the lowest ranking adult female has promoted her
rank independently, following the disappearance of her only
female associate and during her pregnancy, when she was
probably subjected to high risk of predation.
4. Following troop fission, most females chose to
improve their own rank position by adopting the AYS
strategy (Abandon Your immediate Superior in rank), rather
than joining associates. It is suggested that the resident
males were responsible for the initiation of troop fission,
in order to decrease the high cost of sexual competition to
them, by reducing the number of males in each daughter
troop. High intensity of competition between males was the
result of the high female reproductive success. Risk of
predation, and therefore the cost to individual females,
increased after fission.
This study may present an additional
accumulating
behavioural
evidence on
adaptations
environmental conditions.
the
of
flexibility
primates
example to
of social and
to various environmental conditions.
Description
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1993.
Keywords
Baboons--KwaZulu-Natal--Mkuzi Game Reserve--Behaviour., Chacma baboon., Theses--Zoology.