PHYSIOLOGICAL ECOLOGY OF HOWLERS (ALOUATTA) - ENERGETIC AND DIGESTIVECONSIDERATIONS AND COMPARISON WITH THE COLOBINAE

Remarkably little attention has been focused on the physiological ecol ogy of free-ranging primates. Yet without such information it may prov e difficult to advance our understanding of factors influencing the di etary behavior of wild primates much beyond its present state. Mantled howlers (Alouatta palliata) have been studied in terms of some featur es of physiological ecology. Results of this work have helped to clari fy some factors influencing howler and other primate food choices in t he natural environment and have called into question various assumptio ns about leaf-eating primates. For example, though howlers eat conside rable foliage, they do not exhibit a lower than predicted basal metabo lic rate, nor do available data suggest that secondary compounds stron gly influence howler food selection. Comparison of howlers with member s of the Colobinae reveals some differences in features of their respe ctive energetic and digestive physiology and raises timely issues for future research.