American Journal of Primatology 70:505–509 (2008) BRIEF REPORT Behavioral Effects of Introducing Pied Tamarin (Saguinus bicolor) to Black Howler Monkey (Alouatta caraya) and White-Faced Saki (Pithecia pithecia) in a Zoological Park LYDIA GENTRY 1 AND SUSAN W. MARGULIS 1,2Ã 1 Division of Biological Sciences, University of Chicago, Chicago, Illinois 2 Lincoln Park Zoo, Chicago, Illinois Mixed-species primate exhibits are becoming more common in zoological parks as a means to display a diverse array of animals both more naturalistically and with more economy of space. Here, we describe behavioral changes during the introduction process of a pair of pied tamarins (Saguinus bicolor) to an established group of black howler monkeys (Allouatta caraya) and white-faced saki monkeys (Pithecia pithecia). Data were collected during six phases, representing introductions among the various species and to exhibit space and off-exhibit holding. The pied tamarins were consistently the most active of the three species. Although activity levels of the howler and saki monkeys remained constant throughout, that of the tamarins declined as the introduction progressed. Several episodes of aggression between the tamarins and the sakis were observed, but did not coincide with patterns predicted by previous intra-specific introductions. The three-species mix remained stable for several months; however, escalating aggression ultimately led to the removal of the sakis from the mixed-species exhibit. Despite our mixed results, we contend that only through continued trials, coupled with careful and systematic monitoring, can we ultimately identify stable mixes of species. Am. J. Primatol. 70:505–509, 2008.  c 2008 Wiley-Liss, Inc. Key words: pied tamarin; black howler monkey; white-faced saki monkey; mixed-species exhibits INTRODUCTION Mixed-species exhibits have become more pre- valent in recent years as zoos look for new ways to create naturalistic environments that enrich their animals and educate the public as well as make efficient use of limited exhibit space [Wojciechowski, 2004]. Despite the growing number of mixed-species exhibits and brief reviews of their particular suc- cesses and failures [Ziegler, 2002], there have been relatively few formal studies on the inter-specific interactions, both direct and indirect, which must occur to form a stable, mixed-species primate exhibit. In summer 2005, Lincoln Park Zoo Primate House staff introduced 1.1 pied tamarins (Saguinus bicolor) to an exhibit that already held 1.3 black howler monkeys (Alouatta caraya) and 1.1 white-faced saki monkeys (Pithecia pithecia). We capitalized on this opportunity to systematically observe changes in the animals’ behavior to provide information for use both for the ongoing husbandry of these animals and for future mixed-species introductions. Black howler monkeys and white-faced sakis are both common in mixed-species exhibits [Ziegler, 2002]. Pied tamarins, however, are rarely mixed with other species, in part because they are very active and are known to be aggressive and difficult to keep in captivity [Baker & Pissinatti, 2003; Wormell, 2000]. Only Jersey Wildlife Trust and Cleveland Zoo have housed them with other primates (callitrichids and cebids, respectively) [A. Henderson and M. Brayshaw, personal communication]. However, as wild populations of pied tamarins dwindle [Jun- queira Subira ´, 1998], it is increasingly important to strengthen and expand the captive population. Introductions normally proceed in multiple steps, giving the animals gradually increasing contact with one another. Past observations of intra-specific introductions have shown that at each stage, aggression among individuals will generally increase at first but then return to a pre-introduction baseline [Burks et al., 1998, 2001]. Thus, we expected to observe this pattern of aggression here, although Published online 4 January 2008 in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/ajp.20521 Received 12 July 2007; revised 5 December 2007; revision accepted 6 December 2007 Contract grant sponsor: University of Chicago’s Metcalf Fellow- ship Program. Ã Correspondence to: Susan W. Margulis, Curator of Primates, Lincoln Park Zoo, 2001 N. Clark St., Chicago, IL 60614. E-mail: smargulis@lpzoo.org r r 2008 Wiley-Liss, Inc.