ENERGY-METABOLISM AND FOOD-CONSUMPTION BY WILD HOWLER MONKEYS (ALOUATTA-PALLIATA)

Rates of CO2 production in free-living and captive howler monkeys were measured using doubly labeled water, and assimilation of energy from natural foods was determined. Results permit construction of a field energy budget and estimation of the feeding rate of these arboreal, plant-eating primates. Field metabolic rates averaged 355 kJ/kg per day (.apprxeq. 2 .times. basal metabolic rate). Assimilation of the energy in a fruit and leaf diet was .apprxeq. 40%. Feeding rate in the field may be .apprxeq. 54 g dry matter/kg per day or .apprxeq. 90 kg dry matter/ha per yr.