Doctoral Dissertation Research: Habitat Effects on Positional Behavior and Fine Branch Use in Arboreal Cercopithecid Monkeys

Yale University, New Haven CT

Investigators

Abstract

Biologists and anthropologists interested in anatomy, evolution, and behavior rely on the interrelationship of these elements to interpret both living and extinct primate morphological and behavioral adaptations. However, the complex interaction of phylogenetic history, current behavioral specializations, and habitat characteristics makes this exercise difficult. More specifically, debate exists on whether primate positional behavior and support use are canalized and fixed based on phylogenetic constraints, or are highly flexible and context specific. The lack of studies investigating variation in positional behavior and support use across habitats and seasons leads to assumptions concerning primate adaptations and the use of a given habitat. These issues challenge morphologists and ecologists engaged in constructing "typical" profiles of positional behavior for primate species, which are ultimately used to reconstruct evolutionary history. These questions have become particularly relevant in the study of African arboreal cercopithecid monkeys. Results of comparative studies of multiple taxa between two sites (Tai Forest, Ivory Coast, and Kibale Forest, Uganda) vary in certain aspects of positional behavior and support use, especially for the red colobus monkey (Piliocolobus badius), which was studied at both sites. This suggests that the influence of habitat on positional behavior and support use requires further study. Mr. Aronsen's research would contribute to this debate by comparing positional behavior, support use, and habitat preferences in three arboreal monkeys (red colobus, Piliocolobus badius; redtailed monkeys, Cercopithecus ascanius; and grey-cheeked mangabeys, Lophocebus albigena) at Ngogo, located within the Kibale National Park of Uganda. Mr. Aronsen will record data on positional behavior and support use using continuous focal sampling and group scans of highly habituated groups in each species. Habitat structure and patterns of use will be measured using daily follows, transects, and phenological surveys. Primary focus will be placed on fine branch use in all taxa, as these smallest available supports represent a key area for foraging; they are also the most difficult to navigate, thus indicating varying positional and support preferences across taxa and body sizes. These data will then be compared to similar data available from neighboring Kanyawara (for all three species) and the Tai forest (for P. badius). Mr. Aronsen's research has broad implications beyond the study of Kibale monkeys. While his study will examine a significant problem in primate evolutionary biology, it will also inform decisions regarding conservation of primates and their habitats. By examining how flexible or static their behavior is given forest disturbance or logging, one can evaluate the potential impact humans may have on a primate population's overall health and survival. He will also collaborate with Ugandan researchers and field assistants, and share his results and methods to increase knowledge of these issues. This research will also allow him to train and educate students to further study nonhuman primates in their native habitat. Finally, his conclusions will be made available for other researchers to compare other primate species and habitats beyond Africa, thus developing a more comprehensive portrait of primate biology, behavior, and evolution.