Thomas Langurs: Ecology, Sexual Conflict and Social Dynamics
The Thomas langur (Presbytis thomasi) is a colobine species endemic to northern Sumatra, Indonesia. Despite their limited distribution, this species may provide insights into the socio-ecology of folivorous primates. Predictions of the socio-ecological model (van Schaik 1989) suggest that colobine primates feed from nonmonopolizable food sources. Females are therefore expected to experience mainly within-group scramble competition. When this type of competition prevails, the female dominance hierarchy will not be despotic, and female coalitions against other female group members will be rare. Moreover, females may disperse between groups. Many folivorous primates, however, do not fit this predicted pattern (Sterck 1999; Chapman and Pavelka 2005). Some species are presumed to lack scramble competition because group sizes are relatively small and grouping does not seem to entail costs, also known as the folivore paradox (Steenbeek and van Schaik 2001). It has been suggested that not food competition, but male sexual strategies may limit their group size (Crockett and Janson 2000). Different connections between food competition, sexual strategies, and social behavior may exist in folivorous primates, and the Thomas langur may represent one possible connection.
The Thomas langur is a relatively well-studied colobine monkey. Their food sources, food competition, and the effect of group size on behavior have been determined. In addition, male sexual strategies have been investigated, and the dynamics of their social system are well documented. This allows an exploration of the fit and deviations in the predictions of the socio-ecological model and the importance of male sexual strategies for female behavior. Similar social dynamics are found in a number of other Asian colobines (Sterck 1998), a one-male red colobus population (Colobus badius: Marsh 1979) and mountain gorillas (Gorilla gorilla beringei: Harcourt et al. 1976; Watts 1989; Robbins and Sawyer 2007). Therefore, understanding Thomas langur’s social dynamics may suggest an explanation for the behavior of folivorous species with a similar social organization and may generate hypotheses concerning folivorous species with a different social organization. In this chapter, we review the distribution, ecology and behavior of the Thomas langur and explore how their social dynamics relate to ecology and sexual strategies.
KeywordsHome Range Size Resident Male Food Competition Loud Call Sexual Strategy
We gratefully acknowledge the co-operation and support of the Indonesian Institute of Science (LIPI, Jakarta), the Indonesian Nature Conservation Service (PHPA) in Jakarta, Medan, and Kutacane (Gunung Leuser National Park Office), Universitas National (UNAS, Jakarta), Universitas Syiah Kuala (UNSYIAH, Banda Aceh), and the Leuser Development Program (LDP, Medan), especially M. Griffiths and Dr. K. Monk. We also thank the LDP staff in Ketambe, especially Abu Hanifah Lubis, for providing an excellent research environment and strong logistical support. We thank a large number of assistants and students for helping with data collection, without their hard work, this long-term study would not have been possible. Financial support was generously provided by the Netherlands Foundation for the Advancement of Tropical Research (WOTRO), the Treub Foundation, the Dobberke Foundation and the Lucie Burgers Foundation for Comparative Behavior Research. Jan van Hooff and Carel van Schaik are also acknowledged for their support throughout the whole study. We thank the European Commission and the Government of Indonesia as the funding agencies for the Leuser Development Program.
- Borries C, Koenig A (2008) Reproductive and behavioral characteristics of aging in female Asian colobines. In: Atsalis S, Margulis SW, Hof PR (eds) Primate reproductive aging: cross-taxon perspectives on reproduction. Karger, Basel, pp 80-102Google Scholar
- Cheney DL, Seyfarth RM (1990) How monkeys see the world. Chicago University Press, ChicagoGoogle Scholar
- Hausfater G, Hrdy SB (1984) Infanticide: comparative and evolutionary perspectives. Aldine, New YorkGoogle Scholar
- Marshall AJ, Ancrenaz M, Brearley FQ, Fredriksson GM, Ghaffar N, Heydon M, Husson SJ, Leighton M, McConkey KR, Morrogh-Bernard HC, Proctor J, van Schaik CP, Yaeger C, Wich SA (2009) The effects of forest phenology and floristics on populations of Bornean and Sumatran orangutans. In: Wich SA, Utami Atmoko SS, Mitra Setia T, van Schaik CP (eds) Orangutans: Geographic variation in behavioral ecology and conservation. Oxford University Press, New York, pp 97-118Google Scholar
- Morrogh-Bernard HC, Husson SJ, Knott CD, Wich SA, van Schaik CP, van Noordwijk MA, Lackman-Ancrenaz I, Marshall AJ, Kanamori T, Kuze N, Bin Sakong R, Bin Sakong R (2009) Orangutan activity budgets and diet. In: Wich SA, Utami Atmoko SS, Mitra Setia T, van Schaik CP, van Schaik CP, van Schaik CP (eds) Orangutans: Geographic variation in behavioral ecology and conservation. Oxford University Press, New York, pp 119-134Google Scholar
- Shepherd CR, Sukumaran J, Wich SA (2004) Open season: an analysis of the pet trade in Medan, Sumatra 1997-2001. TRAFFIC Southeast Asia, Petaling Jaya, MalaysiaGoogle Scholar
- Steenbeek R (1999a) Female choice and male coercion in wild Thomas’s langurs. Unpublished Ph.D. dissertation, Utrecht UniversityGoogle Scholar
- Steenbeek R, Sterck EHM, de Vries H, van Hooff JARAM (2000) Costs and benefits of the one-male, age-graded and all-male phase in wild Thomas’s langur groups. In: Kappeler PM (ed) Primate Males. Cambridge University Press, Cambridge, pp 130-145Google Scholar
- Sterck EHM (1995) Females, foods and fights. Unpublished Ph.D. dissertation, Utrecht University, UtrechtGoogle Scholar
- Supriatna J, Mittermeier RA (2008) Presbytis thomasi. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 18 Nov 2008
- Trivers RL (1972) Parental investment and sexual selection. In: Campbell B (ed) Sexual selection and the descent of man. Aldine, Chicago, pp 136-179Google Scholar
- van Schaik CP (1989) The ecology of social relationships amongst female primates. In: Standen V, Foley RA (eds) Comparative Socioecology. Blackwell, Oxford, pp 195-218Google Scholar
- van Schaik CP (1996) Social evolution in primates: the role of ecological factors and male behaviour. Proc. Brit. Acad. 88:9-31Google Scholar
- van Schaik CP, Monk KA, Robertson JMY (2001) Dramatic decline in orang-utan numbers in the Leuser Ecosystem, Northern Sumatra. Oryx 35:14-25Google Scholar
- Whitten AJ, Damanik SJ, Jazanul A (1987) & Nazaruddin H. Gadjah Mada University Press, The Ecology of Sumatra, Yogyakarta, IndonesiaGoogle Scholar
- Wich SA, Meijaard E, Marshall AJ, Husson S, Ancrenaz M, Lacy RC, van Schaik CP, Sugardjito J, Simorangkir T, Traylor-Holzer K, Doughty M, Supriatna J, Dennis R, Gumal M, Knott CD, Singleton I (2008a) Distribution and conservation status of the orang-utan (Pongo spp.) on Borneo and Sumatra: how many remain? Oryx 42:329-339CrossRefGoogle Scholar
- Wilson WL, Wilson CC (1975) Species-specific vocalizations and the determination of phylogenetic affinities of the Presbytis aygula-melalophos group in Sumatra. In: Kondo S, Kawai M, Ehara A (eds) Contemporary Primatology. S. Karger, Basel, pp 459-463Google Scholar