Mixed-species tamarin groups (Saguinus fuscicollis and Saguinus labiatus) in northern Bolivia

Mixed-species groups of red-bellied (Saguinus labiatus) and saddle-back (Sa­guinus fuscicollis) tamarins were studied during a 7 month field study in northern Bolivia. Mixed-species troops were common throughout the study area, being encountered in more than 80 % of tamarin observations. Mean monospecific group size was slightly larger for S. labiatus, but the values for both species were fairly similar. Both species overlapped in use of many plant resources, but in most cases the larger-bodied . S. labiatus led the way to, and were first to enter such resources, while the smaller-bodied S. fuscicollis were subordinate and only entered plant resources and ate after their congeners departed. Resource use and foraging strategies are examined, as is the use of Ochroma lagopus and Chorisia speciosa as nectar sources by S. fuscicollis, The species are compared and contrasted in terms of their use of habitat, and results are discussed in the context of other published work.