Foraging strategies, diet and competition in olive baboons
Abstract
Savannah baboons are amongst the most intensively studied taxa
of primates, but our understanding of their foraging
strategies and diet selection, and the relationship of these
to social processes is still rudimentary. These issues were
addressed in a 12-month field study of olive baboons (Papio
anubis) on the Laikipia plateau in Kenya.
Seasonal fluctuations in food availability were closely
related to rainfall patterns, with the end of the dry season
representing a significant energy bottleneck. The
distribution of water and of sleeping sites were the
predominant influences on home range use, but certain
vegetation zones were occupied preferentially in seasons when
food availability within them was high.
The influence of rainfall on monthly variation in dietary
composition generally mirrored inter-population variation.
Phytochemical analysis revealed that simplistic dietary
taxonomies can be misleading in the evaluation of diet
quality. Food preferences were correlated with nutrient and
secondary compound content. The differences between males and
females in daily nutrient intakes were smaller than expected
on the basis of the great difference in body size; this was
partly attributable to the energetic costs of reproduction,
and possibly also to greater energetic costs of
thermoregulation and lower digestive efficiency in females.
A strongly linear dominance hierarchy was found amongst the
adult females. Dominance rank was positively correlated with
food ingestion rates and daily intakes, but not with time
spent feeding or with dietary quality or diversity. In a
provisioned group, high-ranking females occupied central
positions, while low-ranking females were more peripheral and
were supplanted more frequently. In the naturally-foraging
group, the intensity of competition was related to the pattern
of food distribution, but not to food quality, and was greater
in the dry season than in the wet season. The number of
neighbours and rates of supplanting were correlated with rank,
and evidence was presented that high-rankers monopolised
arboreal feeding sites.
Type
Thesis, PhD Doctor of Philosophy
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