Resource use by howler monkeys (Alouatta palliata) in the rain forest of Los Tuxtlas,Veracruz, Mexico

The feeding preferences of howler monkeys at their northernmost distribution in the Neotropics are reported for an annual cycle. A remarkable selectivity for 27 species representing 15 families was observed. The Moraceae and Lauraceae plant families were the most important in the diet. The howlers spent an almost equal proportion of their feeding time eating leaves and fruit, and displayed a marked preference for young leaves and mature fruit. The consumption of different plant parts was markedly seasonal and the howlers’ ranging behavior was closely associated with the availability of young leaves and mature fruit. Their home range was unusually large (ca. 60 ha) for howlers and the food species exploited occur at very low densities (93%, ≤ 4 ind/ha). They chose food items richer in protein and energy. Alkaloid compounds, present in some of the leaves, play a secondary role in their dietary selectivity.