Anthropology, Washington University in St. Louis
Friday 189, Plaza Level
I examined the diet of a population of black howler monkeys (Alouatta pigra) isolated on an island of mangrove forest on the Pantanos de Centla Biosphere Reserve in Tabasco, Mexico. It is unusual for large folivorous primates to inhabit solely mangrove due to low plant species diversity, many of which are specially adapted to saline conditions. Compared with lowland tropical forests, which can contain hundreds of species in a handful of hectares, plant diversity in American mangroves is limited to less than 15 species. Howlers selectively eat from an average of 60 species of plants over an annual basis to obtain adequate nutrients and avoid toxins. I hypothesized that the mangrove howlers may eat fewer leaves than other howler populations, exploit novel foods, and that food plants would reflect a high protein to fiber ratio. Through both wet and dry seasons, I collected data on the monkeys’ daily activities and plant choices for food and non-food use. I assessed the phytochemical components of these plants and examined seasonal differences. The mangrove howlers used only 12 species for food. When compared to other howler populations, mangrove howlers ate significantly more flowers, more seeds, and less fruit. Leaf consumption was within the range of other howler diets. Protein to fiber ratios were slightly higher in plant products selected as food. An important seasonal difference was the availability of flowers and seeds, providing more protein and zinc to the howlers. The overall health of primate populations may not be limited by habitat diversity.