Dietary and Feeding Differences Between Sympatric Propithecus diadema diadema and Indri indri

We analyzed the dietary profiles and feeding behaviors of Propithecus diadema diadema and Indri indri in a community of animals that reside in midaltitude rain forest within Madagascar's Mantadia National Park. Propithecus diadema diadema ate a diverse mixture of fruits, seeds, flowers and young leaves, while the bulk of the diet of Indri indri consisted of young leaves, which resulted in significantly higher levels of fat and water-soluble carbohydrates in foods eaten by Propithecus diadema diadema. Fiber values of items eaten are high (54% NDF) for both species, though not significantly different between them. The preference for immature foliage by Indri indri suggests that their overall intake of fiber is greater than that of Propithecus diadema diadema, which had a high proportion of non-leaf material in their diet. We propose that differences in gut morphology between the two indriids contribute to their disparate diets. Levels of secondary compounds were high in certain food items, but overall they are also not significantly different between the two indriid diets. Propithecus diadema diadema exhibited a strong preference for 2 alkaloid-containing seed species, while no food of Indri indri contained alkaloids. In addition, Propithecus diadema diadema consumed a higher diversity of plant species on a daily/yearly basis, exhibited more feeding bouts on a daily basis, and their feeding bouts (on young leaves, fruit and flowers) are significantly shorter in duration than those of Indri indri. Furthermore, Propithecus diadema diadema had twice the number of geophagic episodes of Indri indri.