A preliminary analysis of the chemistry and color of leaves ingested by four colobine species in Vietnam
It appears that all catarrhine primates can equally differentiate leaf color. However, it remains to be seen if leaf monkeys, particularly sympatric and congeneric species, select leaves that differ mechanically and chemically, and if these leaf characteristics are associated with certain spectrographic signatures. This study examines variation in the chemical composition and color of leaves selected by four colobine species at the Endangered Primate Rescue Center (EPRC), Cuc Phuong National Park, Vietnam. The location of the EPRC permits us to provision the study species with a range of foods found in their natural habitat. The inclusion of Pygathrix nemaeus, P. cinerea, Trachypithecus delacouri, and T. laotum hatinhensis permit both intra- and intergeneric comparisons. By providing the primates with monospecific bundles of leaves we were able to rank the most preferred, moderately preferred, and least preferred foods. The toughness of all selected foods was found to be statistically comparable among the four study species. However, the species appear to partition their diets according to the percentage of protein and secondary chemical compounds found in selected leaves. Furthermore, the chemical make-up of the leaves is correlated with particular shades of green and red.