Ten years of mixed-species troops at Belfast Zoological Gardens

In the wild, tamarin species form some of the longest lasting and most cohesive of primate mixed-species associations. Despite this, they are usually exhibited in captivity as single-species troops. Here we describe and integrate both published and unpublished research conducted at Belfast Zoological Gardens, Northern Ireland, concerning the formation and maintenance of mixed-species troops of the saddlebacked tamarin (Saguinus fuscicollis) and the red-bellied or white-lipped tamarin (Saguinus labiatus). Over a 10-year period, a protocol for successful mixing was established, and at least 26 mixed-species troops were formed and maintained offexhibit to the public with few or no problems; some individual animals lived in such troops for over 3.5 years. Detailed research comparing single- and mixed-species troops of tamarins demonstrates that both species actively attend to and respond to each other in mixed-species troops, and that they alter their behaviour in ways that are complementary and potentially beneficial. Both tamarin species successfully bred and reared offspring whilst in mixed-species troops. Free-ranging mixedspecies troops showed a high degree of cohesion, demonstrating that such troops in captivity are not based simply on the species tolerating each other’s presence in a confined space. An informative exhibit of a tri-specific troop of both the saddlebacked and red-bellied tamarin with Goeldi's monkey (Callimico goeldii), another species with whom the tamarins associate in nature, was opened to the public in 1997.