Tamarin polyspecific associations: Forest utilization and stability of mixed-species groups

Niche separation is likely to play a key role in the formation of mixed-species groups. Saddle-backed tamarins (Saguinusfuscicollis) were studied at three sites with different primate communities in northern Bolivia: (1) with red-bellied tamarins, S. labiatus; (2) with emperor tamarins, S. imperator; and (3) without a congeneric species. The degree of association is higher between S. labiatus and S. fuscicollis than between S. imperator and S. fuscicollis and is related to differences in forest utilization between associating pairs. Niche separation is found to be greater between S. labiatus and S. fuscicollis than between S. fuscicollis and S. imperator. The mean height and habitat utilization of S. fuscicollis does not differ greatly across the three sites, nor does the height of tamarins in and out of association. It is concluded that combined with differences in body size and dietary overlap, vertical segregation plays an important role in tamarin polyspecific associations (increasing the potential of both foraging and anti-predatory benefits) and that this is not a consequence of vertical displacement of S. fuscicollis by its dominant congeners