The hoatzin is the only folivorous bird known to have foregut fermentation. Since changes in plant availability must influence the dietary choices and affect the structure of the digestive microbiota in herbivores, we hypothesized that hoatzins from different habitats would have different crop microbial communities. To test this hypothesis we characterized the crop microbiota of three birds in two locations in Venezuela, the rivers Orinoco and Cojedes. We compared plant availability and foraging behavior in the two locations, and used a 16S rDNA microarray, to characterize crop bacteria.National Science Foundation, NSF: IOS 0716911, DDIG 0709840 and HRD #0734826 and University of Puerto Rico, Río Piedras Campus