Keren Klass
M.A. Conservation Biology, 2010

Dominance and agonism among wild blue monkeys (Cercopithecus mitis stuhlmanni) in the Kakamega Forest, Kenya

Klass
Dominance status is an important social variable influencing individual behavior and life history in group-living animals. The causes and consequences of intragroup agonism and dominance relationships are a central focus of primate socioecology. I examined the dominance relationships and hierarchy in a forest-dwelling guenon, the blue monkey (Cercopithecus mitis stuhlmanni), using data from six groups spanning 12 years and 24,996 agonistic interactions. I also examined methodological questions relating to (i) similarities in dominance rankings produced with different methods and (ii) the effect of the percentage of unknown relationships in the dominance matrix on the stability of the rank output and two descriptive indices, linearity and steepness. The blue monkey dominance hierarchy is best described by a combination of the I&SI ordinal ranking algorithm (de Vries 1995, 1998) and the David‟s score cardinal ranking method (David 1987). My methodological analyses showed that matrices with ≥ ~25% unknown relationships lead to inconsistent ranking results, regardless of the dominance index used. Blue monkeys have moderately but significantly steep and linear dominance hierarchies, high directional consistency indices, low rates of agonism, and relatively high proportions of bidirectional dyadic dominance relationships. Maternal rank is a central determinant of an individual female‟s adult rank in the dominance hierarchy, and juveniles mirror maternal rank closely. There was considerable variation among groups and over time within the study population in linearity, steepness, stability of rank and per capita agonism rates. Group size and access to high value human-derived foods may be partially responsible for this variation. This study has shown that blue monkeys have moderately despotic, tolerant and nepotistic dominance hierarchies and are perhaps best classified according to Sterck et al.‟s (1997) model as “Resident-Nepotistic-Tolerant.”  The relative agreement between model predictions and the characteristics of blue monkey dominance hierarchies highlights the likely role of ecology in shaping intragroup social relationships in this species. Blue monkeys resemble ecologically similar species in many aspects of their dominance system but retain a nepotistic structure, which is highly conserved in the Cercopithecinae. These results can contribute to future studies examining the central hypotheses and predictions of socioecological models and to future studies of the role of phylogeny in shaping group social structure.

After finishing her MA, Keren worked on environmental policy in Israel, and then joined a PhD program at the University of Toronto.


Publications from Master's research: