The effect of male parallel dispersal on the kin composition of groups in white-faced capuchins Eva C. Wikberg a, * , Katharine M. Jack b , Fernando A. Campos a, c , Linda M. Fedigan c , Akiko Sato a , Mackenzie L. Bergstrom c , Tomohide Hiwatashi a , Shoji Kawamura a a Department of Integrated Biosciences, University of Tokyo, Kashiwa, Chiba, Japan b Department of Anthropology, Tulane University, New Orleans, LA, U.S.A. c Department of Anthropology, University of Calgary, Calgary, Alberta, Canada article info Article history: Received 22 February 2014 Initial acceptance 16 April 2014 Final acceptance 7 July 2014 Published online MS. number: 14-00147R Keywords: capuchins coalition dispersal cooperation kin bias parallel dispersal single dispersal Sex-biased dispersal can reduce kin cooperation and kin competition in the dispersed sex. However, this may not be the case when group-living animals engage in parallel dispersal, which occurs when an individual transfers between groups together with other animals or immigrates alone into a group that contains familiar animals. Despite this potential effect on kin cooperation and competition, few studies have thoroughly investigated how parallel dispersal affects the kin composition of groups. To further our understanding of this topic, we investigated the effect of parallel dispersal on access to coresident kin in male white-faced capuchins, Cebus capucinus. Between 2006 and 2013, we collected demographic and genetic data from two to five groups in Sector Santa Rosa, Costa Rica. We genotyped 41 females and 39 males at 14 short tandem repeat loci, and we calculated their estimated relatedness values. The majority of males dispersed in parallel, and parallel dispersing males were more closely related to one another than were other males. Parallel immigrant males and natal females resided with a similar number of same-sex kin. Single immigrant males in multimale groups rarely resided with male kin, and they resided with fewer same-sex kin than did parallel immigrant males and natal females. Because parallel dispersal offers an opportunity for males to form long-lasting cooperative relationships with familiar kin, this dispersal pattern should be taken into account in future models of the evolution of social structure. © 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Dispersal can be costly because it may increase predation risk and aggression from conspecifics while reducing foraging efficiency and access to familiar social partners (Bonte et al., 2012; Isbell & Van Vuren, 1996). Perhaps to mitigate these costs, dispersing in- dividuals in some birds (reviewed in Riehl, 2013), social carnivores (Frame, Malcolm, Frame, & Vanlawick, 1979; Packer, Gilbert, Pusey, & O'Brien, 1991) and primates (reviewed in Schoof, Jack, & Isbell, 2009) engage in parallel dispersal. Parallel dispersal occurs when animals transfer between groups together with familiar animals or when they immigrate alone into a group that contains familiar animals (van Hooff, 2000). The potential benefits of parallel dispersal include lowered predation risk while transferring be- tween groups, reduced aggression from resident animals in the new group, continued access to familiar coalitionary partners (Alberts & Altmann, 1995; Cheney & Seyfarth, 1983; Schoof et al., 2009) and enhanced inclusive fitness (Pope, 1990). Because parallel dispersal enables dispersing animals to main- tain long-term bonds with familiar animals, it may have important fitness consequences, particularly when the dispersing sex relies on coalitions to gain mating opportunities. In some species with male parallel dispersal, coalitions of males have greater success at pro- curing groups of females and high-quality territories, higher sur- vival and/or greater reproductive success (red howler, Alouatta seniculus: Pope, 1990; Sekulic, 1983; tamarins, Saguinus spp.: Baker, 1991; Garber, Encarnaci on, Moya, & Pruetz, 1993; L€ ottker, Huck, & Heymann, 2004; lion, Panthera leo: Packer et al., 1991; white- faced capuchin, Cebus capucinus: Fedigan & Jack, 2004; Jack & Fedigan, 2004a, 2004b; acorn woodpecker, Melanerpes for- micivorus: Koenig, Walters, & Haydock, 2011; Arabian babbler, Turdoides squamiceps: Ridley, 2012). Despite the formation of co- alitions, it is often only the most dominant male that experiences immediate gains in terms of reproductive opportunities (Díaz- Mu~ noz, 2011; Jack & Fedigan, 2006; Krakauer, 2005; Krutzen, Barre, Connor, Mann, & Sherwin, 2004; Muniz et al., 2010; Packer et al., 1991; Pope, 1990; Ridley, 2012). None the less, weaker males may be unable to take over or gain membership within a bisexual group on their own, and their best strategy may be to * Correspondence: E. C. Wikberg, Department of Integrated Biosciences, University of Tokyo, Bioscience Building 502, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan. E-mail address: wikberg@ib.k.u-tokyo.ac.jp (E. C. Wikberg). Contents lists available at ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav http://dx.doi.org/10.1016/j.anbehav.2014.07.016 0003-3472/© 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Animal Behaviour 96 (2014) 9e17