DIET AND FEEDING ECOLOGY OF SADDLE-BACK (SAGUINUS-FUSCICOLLIS) AND MOUSTACHED (SAGUINUS-MYSTAX) TAMARINS IN AN AMAZONIAN TERRA FIRME FOREST

The feeding ecology of two small-bodied primate species-saddle-back (Saguinus fuscicollis avilapiresi) and moustached tamarins (S. mystax pileatus)-occurring in stable, mixed-species groups was studied in a terra firme forest site in the upper Urucu River, Amazonas, Brazil. Ecological data are based primarily on one mixed-species group of 5-8 saddle-back and 8-10 moustached tamarins. The overall vegetative and animal-prey components of each tamarin species' diet, their selection of food species, and the seasonal variation in their use of plant resources are described, and compared to those of callitrichids elsewhere. The extremely diverse diet of tamarins included at least 136 tree, 33 vine and liana, 12 epiphyte and nine shrub species, as well as a wide range of prey items. They fed primarily on ripe fruit pulp of most of these species for most of the year, but shifted to floral nectar and plant exudates of a few key plant species during the dry season. Taxonomic overlap in plant diet was nearly complete between the two tamarin species, but they diverged considerably in their prey capture techniques. Saddle-backs used the low forest understorey, and manipulatively searched for sedentary prey concealed within discrete, usually rigid, microhabitats, whereas moustached tamarins used the midstorey where they visually searched for mobile prey well exposed on foliage. These and other feeding and foraging patterns are discussed in the light of other callitrichid species studied to date.