14 - Seasonality, social organization, and sexual dimorphism in primates  pp. 401-442

Seasonality, social organization, and sexual dimorphism in primates

By J. Michael Plavcan, Carel P. van Schaik and W. Scott McGraw

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Introduction

Primates live in habitats in which food abundance and other resources fluctuate over time, usually on a seasonal basis, and space. This variation affects the lives of primates in many ways, from behavioral ecology to reproduction (see Chapters 3 and 11). In this chapter, we explore how environmental and behavioral seasonality affect sexual dimorphism.

Sexual dimorphism in body and canine size among primates generally is viewed as primarily a consequence of sexual selection operating through the mechanism of male–male competition for mates (Leutenegger & Kelly 1977; Clutton-Brock et al. 1977; Kay et al. 1988; Plavcan & van Schaik 1992, 1997; Ford 1994; Lindenfors & Tullberg 1998) and modified by female choice for male traits (Plavcan 2004). Sexual dimorphism can be affected by environmental seasonality in two independent ways (see Fig. 14.1): first through the indirect impact of seasonality on the potential for mate monopolization (Mitani et al. 1996a; Nunn 1999; Pereira et al. 2000), and second through the direct impact of seasonality on male and female body size (Albrecht 1978; Turner et al. 1997). In the first case, phenological or climatic seasonality brings about the simultaneous presence of multiple cycling females due to reproductive seasonality and also may favor larger female group size. These effects in turn should affect the number of males present in a group, and patterns of male–male competition and resulting reproductive skew – in other words, several aspects of social organization and the mating system, all of which are tied to sexual dimorphism.

Albrecht, G. H. & Miller, J. M. A. (1993). Geographic variation in primates: a review with implications for interpreting fossils. In Species, Species Concepts, and Primate Evolution, ed. W. H. Kimbel & L. B. Martin. New York: Plenum Press, pp. 211–37.
Albrecht, G. H. (1978). The Craniofacial Morphology of the Sulawesi Macaques. Basel: Karger.
Albrecht, G. H.(1980). Latitudinal, taxonomic, sexual, and insular determinants of size variation in pigtail macaques, Macaca nemestrina. International Journal of Primatology, 1, 141–52.
Albrecht, G. H.(1983). Geographic variation in the skull of the crab-eating macaque, Macaca fascicularis (Primates: Cercopithecidae). American Journal of Physical Anthropology, 60, 169.
Albrecht, G. H., Jenkins, P. D., & Godfrey, L. R. (1990). Ecogeographic size variation among the living and subfossil prosimians of Madagascar. American Journal of Primatology, 22, 1–50.
Altmann, J. (2000). Models of outcome and process: predicting the number of males in primate groups. In Primate Males, ed. P. M. Kappeler. Cambridge: Cambridge University Press, pp. 236–47.
Altmann, S. A. (1959). Field observations on a howling monkey society. Journal of Mammalogy, 40, 317–30.
Altmann, S. A.(1962). A field study of the sociobiology of the rhesus monkey, Macaca mulatta. Annals of the New York Academy of Sciences, 102, 338–435.
Andelman, S. J. (1986). Ecological and social determinants of cercopithecine mating patterns. In Ecological Aspects of Social Evolution: Birds and Mammals, ed. D. I. Rubenstein & R. W. Wrangham. Princeton: Princeton University Press, pp. 201–16.
Andersson, M. (1994). Sexual Selection. Princeton: Princeton University Press.
Bennett, E. L. & Davies, A. G. (1994). The ecology of Asian colobines. In Colobine Monkeys, ed. A. G. Davies & J. F. Oates. Cambridge: Cambridge University Press, pp. 129–72.
Bennett, E. L. & Sebastian, A. C. (1988). Social organization and ecology of proboscis monkeys (Nasalis larvatus) in mixed coastal forest in Sarawak. International Journal of Primatology, 9, 233–55.
Bernstein, I. S. (1964). A field study of the activities of howler monkeys. Animal Behavior, 12, 92–7.
Bernstein, I. S.(1968). The lutong of Kuala Selangor. Behavior, 32, 1–16.
Bishop, N. H. (1979). Himalayan langurs: temperate colobines. Journal of Human Evolution, 8, 251–81.
Boggess, J. (1976). The social behavior of the Himalayan langur (Presbytis entellus) in Eeastern Nepal. Ph.D. thesis, University of California.
Bolin, I. (1981). Male parental behavior in black howler monkeys (Alouatta palliata pigra) in Belize and Guatemala. Primates, 22, 349–60.
Boonratana, R. (2000). Ranging behavior of proboscis monkeys (Nasalis larvatus) in the lower Kinabatangan, Northern Borneo. International Journal of Primatology, 21, 497–518.
Braza, A. A., Alvarez, A., & Azacarte, T. (1981). Behavior of the red howler monkey (Alouatta seniculus) in the llanos of Venezuela. Primates, 22, 459–73.
Carpenter, C. R. (1934). A field study of the behavior and social relations of howling monkeys. Comparative Psychology Monographs, 10, 1–168.
Carpenter, C. R.(1962). Field studies of a primate population. In Roots of Behavior, ed. E. L Bliss. New York: Harper and Row, pp. 286–94.
Chivers, D. J. (1969). On the daily behavior and spacing of howling monkey groups. Folia Primatologica, 10, 48–102.
Clarke, M. R., Zucker, E. L., & Scott, N. J. (1986). Population trends of the mantled howler groups of La Pacifica, Guanacaste, Costa Rica. American Journal of Primatology, 11, 79–88.
Clutton-Brock T. H., Harvey, P. H., & Rudder, B. (1977). Sexual dimorphism, socionomic sex ratio and body weight in primates. Nature, 269, 191–5.
Clutton-Brock, T. H. (1975). Feeding behavior of red colobus and black and white colobus in East Africa. Folia Primatologica, 23, 165–207.
Clutton-Brock, T. H.(1989). Mammalian mating systems. Proceedings of the Royal Society, London, Series B, 236, 339–72.
Coelho. A. M., Coelho, L. S., Bramblett, C. A., Bramblett, S. S., & Quick, L. B. (1976). Ecology, population characteristics and sympatric associations in primates: a bioenergetic analysis of howler and spider monkeys in Tikal. Yearbook of Physical Anthropology, 20, 96–135.
Collias, N. & Southwick, C. (1952). A field study of population density and social organization in howling monkeys. Proceedings of the American Philosophical Society, 96, 143–56.
Cords, M. (1984). Mating patterns and social structure in redtail monkeys (Cercopithecus ascanius). Zeitschrift fur Tierpsychologie, 64, 313–29.
Cords, M.(2000). The number of males in guenon groups. In Primate Males, ed. P. M. Kappeler. Cambridge: Cambridge University Press, pp. 84–96.
Crockett, C. M. & Eisenberg, J. F. (1987). Howlers: variation in group size and demography. In Primate Societies, ed. B. Smuts, D. Cheney, R. Wrangham, & T. T. Struhsaker. Chicago: University of Chicago Press, pp. 54–68.
Crockett, C. M. (1984). Emigration by female red howler monkeys and the case for female competition. In Female Primates: Studies by Female Primatologists, ed. M. F. Small. New York: Alan R. Liss, pp. 159–73.
Curtin, R. A. (1975). The socio-ecology of the common langur, Presbytis entellus, in the Nepal Himalaya. Ph.D. thesis, University of California.
Davies, A. G., Oates, J. F., & Dasilva, G. L. (1999). Patterns of frugivory in three West African colobine monkeys. International Journal of Primatology, 20, 327–57.
Defler, T. R. (1981). The density of Alouatta seniculus in the eastern llanos of Colombia. Primates, 22, 564–9.
Defler, T. R.(1996). Aspects of the ranging pattern in a group of wild woolly monkeys (Lagothrix lagothricha), American Journal of Primatology, 38, 289–302.
DiBietti, M. S., & Janson, C. H. (2000). Reproductive socioecology of tufted capuchins (Cebus apella nigritus) in Northeastern Argentina. International Journal of Primatology, 22, 127–142.
DiFiore, A. & Rodman, P. S. (2001). Time allocation patterns of lowland woolly monkeys (Lagothrix lagothricha peoppigii) in a neotropical terra firma forest. International Journal of Primatology, 22, 449–80.
Dunbar, R. I. M. & Dunbar, E. P. (1974). Ecology and population dynamics of Colobus guereza in Ethiopia. Folia Primatologica, 21, 188–208.
Dunbar, R. I. M. (1987). Habitat quality, population dynamics, and group composition in colobus monkeys (Colobus guereza). International Journal of Primatology, 8, 299–330.
Dunbar, R. I. M.(1990). Environmental determinants of intraspecific variation in body weight in baboons (Papio spp.). Journal of Zoology, London, 220, 157–69.
Dunbar, R. I. M.(2000). Male mating strategies: a modeling approach. In Primate Males, ed. P. M. Kappeler. Cambridge: Cambridge University Press, pp. 259–68.
Eisenberg, J. F. (1979). Habitat, economy, and society: some correlations and hypotheses for the Neotropical primates. In Primate Ecology and Human Origins, ed. I. S. Bernstein & E. O. Smith. New York: Garland Press, pp. 215–62.
Emlen, S. T. & Oring T. (1977). Ecology, sexual selection, and the evolution of mating systems. Science, 191, 215–33.
Estrada, A. (1982). Survey and census of howler monkeys (Alouatta palliata) in the rain forest of “Los Tuxtlas” Veracruz, Mexico. American Journal of Primatology, 2, 363–72.
Fashing, P. J. (2001). Feeding ecology of guerezas in the Kakamega Forest Kenya: the importance of Moracaceae fruit in their diet. International Journal of Primatology, 22, 579–610.
Fedigan, L. M., Fedigan, L., & Chapman, C. A. (1985). A census of Alouatta palliata and Cebus capucinus in Santa Rosa National Park, Costa Rica. Brenesia, 23, 309–22.
Fishkind, A. S. & Sussman, R. W. (1987). Preliminary survey of the primates of the Zona Protectora and La Selva Biological Station, northeast Costa Rica. Primate Conservation, 8, 63–6.
Fleury, M. & Gautier-Hion, A. (1999). Seminomadic ranging in a population of black colobus (Colobus satanas) in Gabon and its ecological correlates. International Journal of Primatology, 20, 491–510.
Fooden, J. & Albrecht, G. H. (1993). Latitudinal and insular variation of skull size in crab-eating macaques (Primates, Cercopithecidae: Macaca fascicularis). American Journal of Physical Anthropology, 92, 521–38.
Ford, S. M. (1994). Evolution of sexual dimorphism in body weight in platyrrhines. American Journal of Primatology, 34, 221–4.
Freckleton, R. P., Harvey, P. H., & Pagel, M. (2003). Bergmann's rule and body size in mammals. American Naturalist, 161, 821–5.
Freese, C. (1976). Censusing Alouatta palliata and Cebus capucinus in Costa Rican dry forest. In Neotropical Primates: Field Studies and Conservation, ed. R. W. Thorington & P. G. Heltne. Washington, DC: National Academy of Sciences, pp. 4–9.
Galat, G. & Galat-Luong, A. (1976). La colonization de la mangrove par Cercopithecus aethiops sabaeus au Senegal. La Terre et Vie, 30, 3–30.
Galat-Luong, A. & Galat, G. (1979). Quelques observations sur l'ecologie de Procolobus badius oustaleti en Empire Centrafrician. Mammalia, 43, 309–12.
Garland, T., Jr, Dickerman, A. W., Janis, C., & Jones, J. A. (1993). Phylogenetic analysis of covariance by computer simulation. Systematic Biology, 42, 265–92.
Garland, T., Jr, Midford, P. E., & Ives, A. R. (1999). An introduction to phylogenetically based statistical methods, with a new method for confidence intervals on ancestral states. American Zoologist, 39, 374–88.
Gaulin, S. J. C. & Gaulin, C. K. (1982). Behavioral ecology of Alouatta seniculus in Andean cloud forest. International Journal of Primatology, 3, 1–32.
Green, S. (1978). Primate censusing in northern Colombia: a comparison of two techniques. Primates, 19, 537–50.
Greenfield, L. O. & Washburn, A. (1991). Polymorphic aspects of male anthropoid canines. American Journal of Physical Anthropology, 84, 17–34.
Greenfield, L. O. (1992). Relative canine size, behavior, and diet in male ceboids. Journal of Human Evolution, 23, 469–80.
Groves, C. P. (1973). Notes on the ecology and behavior of the Angola colobus (Colobus angolensis P. L. Sclater 1860) in N.E. Tanzania. Folia Primatologica, 20, 12–26.
Hall, K. R. L. & Gartlan, J. S. (1965). Ecology and behavior of the vervet monkey, C. aethiops, Lolui Island, Lake Victoria. Proceedings of the Zoological Society, London, 145, 37–56.
Heltne, P. G., Turner, D. C., & Scott, N. J. (1976). Comparison of census data on Alouatta palliata from Costa Rica and Panama. In Neotropical Primates: Field Studies and Conservation, ed. R. W. Thorington & P. G. Heltne. Washington, DC: National Academy of Sciences, pp. 10–19.
Henzi, S. P., & Lucas, J. W. (1980). Observations on the inter-troop movement of adult vervet monkeys (Cercopithecus aethiops). Folia Primatologica, 33, 220–35.
Herbinger, I., Boesch, C., & Rothe, H. (2001). Territory characteristics among three neighboring chimpanzee communities in the Tai National Park, Cote d'Ivoire. International Journal of Primatology, 22, 143–68.
Hershkovitz P. (1977). Living New World Monkeys (Platyrrhini), Vol. 1. Chicago: University of Chicago Press.
Horwich, R. H. & Johnson, E. D. (1986). Geographical distribution of the black howler (Alouatta pigra) in Central America. Primates, 27, 53–62.
Horwich, R. W. (1983). Species status of the black howler monkey, Alouatta pigra, of Belize. Primates, 27, 53–62.
Isbell, L. A. & Pruetz, J. D. (1998). Differences between vervets (Cercopithecus aethiops) and patas monkeys (Erythrocebus patas) in agonistic interactions between adult females. International Journal of Primatology, 19, 837–56.
Janson, C. H., & Goldsmith, M. L. (1995). Predicting group size in primates: foraging costs and predation risks. Behavioural Ecology, 6, 326–36.
Julliot, C. (1996). Fruit choice by red howler monkeys (Alouatta seniculus) in a tropical rain forest. American Journal of Primatology, 40, 261–82.
Kaplin, B. A. & Moermond, T. C. (2000). Foraging ecology of the mountain monkey (Cercopithecus l'hoesti): implications for its evolutionary history and use of disturbed forest. American Journal of Primatology, 50, 227–46.
Kavanagh, M. (1978). The diet and feeding behavior of Cercopithecus aethiops tantalus. Folia Primatologica, 30, 76–98.
Kay, R. F., Madden, R. H., van Schaik, C. & Higdon, D. (1997). Primate species richness is determined by plant productivity: implications for conservation. Proceedings of the National Academy of Sciences, USA, 94, 13023–7.
Kay, R. F., Plavcan, J. M., Glander, K. E., & Wright, P. C. (1988). Sexual selection and canine dimorphism in New World monkeys. American Journal of Physical Anthropology, 77, 385–97.
Kool, K. M. (1989). Behavioral ecology of the silver leaf monkey, Trachypithecus auratus sondaicus, in the Pangandaran Nature Reserve, West Java, Indonesia. Ph.D. thesis, University of New South Wales.
Lande R. (1980). Sexual dimorphism, sexual selection, and adaptation in polygenic characters. Evolution, 33, 292–305.
Leigh, S. R. & Terranova, C. J. (1998). Comparative perspectives on bimaturism, ontogeny, and dimorphism in lemurid primates. International Journal of Primatology, 19, 723–49.
Leigh, S. R. (1994). Relations between captive and noncaptive weights in anthropoid primates. Zoo Biology, 13, 21–43.
Leigh, S. R., & Shea, B. T. (1995). Ontogeny and the evolution of adult body size dimorphism in apes. American Journal of Primatology, 36, 37–60.
Leutenegger, W. & Kelly, J. T. (1977). Relationship of sexual dimorphism in canine size and body size to social, behavioral and ecological correlates in anthropoid primates. Primates, 18, 117–36.
Lindenfors, P. & Tullberg, B. S. (1998). Phylogenetic analysis of primate size evolution: the consequences of sexual selection. Biological Journal of the Linnean Society, 64, 413–47.
Lindenfors, P. (2002). Sexually antagonistic selection on primate size. Journal of Evolutionary Biology, 15, 595–607.
Maisels, F., Gautier-Hion, A., & Gautier, J. P. (1994). Diets of two sympatric colobines in Zaire: more evidence on seed-eating in forests on poor soils. International Journal of Primatology 15, 681–701.
Marler, P. (1969). Colobus guereza: territoriality and group composition. Science, 163, 93–5.
Martin, R. D., Willner, L. A., & Dettling, A. (1994). The evolution of sexual size dimorphism in primates. In The Differences Between the Sexes, ed. R. V. Short & E. Balaban. Cambridge: Cambridge University Press, pp. 159–200.
McGraw, W. S. (1994). Census, habitat preference and polyspecific associations of six monkeys in the Lomako Forest, Zaire. American Journal of Primatology, 34, 295–307.
McHenry, H. M. (1992). Body size and proportions in early hominids. American Journal of Physical Anthropology, 87, 407–31.
McKey, D. B. & Watermann, P. G. (1982). Ranging behavior of a group of black colobus (Colobus satanas) in the Douala-Edea Reserve, Cameroon. Folia Primatologica, 39, 264–304.
McKey, D. B. (1978). Plant chemical defenses and the feeding and ranging behavior of colobus monkeys in African rain forests. Ph.D. thesis, University of Michigan.
Milton, K. (1982). Dietary quality and demographic regulation in a howler monkey population. In The Ecology of a Tropical Forest, ed. E. G. Leigh, A. S. Rand, & D. M. Windsor. Washington, DC: Smithsonian Institution Press, pp. 273–89.
Mitani, J., Gros-Louis, J., & Richards, A. F. (1996a). Number of males in primate groups: comparative tests of competing hypotheses. American Journal of Primatology, 38, 315–32.
Mitani, J., Gros-Louis, J., & Richards, A. F.(1996b). Sexual dimorphism, the operational sex ratio, and the intensity of male competition in polygynous primates. American Naturalist, 147, 966–80.
Mittermeier, R. A. (1973). Group activity and population dynamics of the howler monkey on Barro Colorado Island. Primates, 14, 1–19.
Mowry, C. B., Decker, B. S., & Shure, D. J. (1996). The role of phytochemistry in dietary choices of Tana River red colobus monkeys (Procolobus badius rufomitratus). International Journal of Primatology, 17, 63–84.
Nakagawa, N. (1999). Differential habitat utilization by patas monkeys Erythrocebus patas) and tantalus monkeys (Cercopithecus aethiops tantalus) living sympatrically in northern Cameroon. American Journal of Primatology, 49, 243–64.
Neville, M. K. (1972). The population structure of red howler monkeys (Alouatta seniculus) in Trinidad and Venezuela. Folia Primatologica, 17, 56–86.
Neville, M. K.(1976). The population and conservation of howler monkeys in Venezuela and Trinidad. In Neotropical Primates: Field Studies and Conservation, ed. R. W. Thorington & P. G. Heltne. Washington, DC: National Academy of Sciences, pp. 101–9.
Newton, P. N. (1987). The social organization of forest hanuman langurs (Presbytis entellus). International Journal of Primatology, 8, 199–232.
Nunn, C. L. (1999). The evolution of exaggerated sexual swellings in primates and the graded-signal hypothesis. Animal Behavior, 58, 229–46.
Oates, J. F. (1977). The social life of black and white colobus monkeys, Colobus guereza. Zeitschrift für Tierpsychologie, 45, 1–60.
Olupot, W., Chapman, C. A., and Brown, C. H. (1994). Mangabey (Cercocebus albigena) population density, group size and ranging: a 20 year comparison. American Journal of Primatology, 32, 197–205.
Oppenheimer, J. R. (1977). Presbytis entellus, the Hanuman langur. In Primate Conservation, ed. H. S. H. Prince Ranier & G. H. Bourne. New York: Academic Press, pp. 469–512.
Palacios, E. & Rodriguez, A. (2001). Ranging pattern and use of space in a group of red howler monkeys (Alouatta seniculus) in a southeastern Colombian rainforest. American Journal of Primatology, 55, 233–51.
Parnell, R. J. (2002). Group size and structure in western lowland gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Republic of Congo. American Journal of Primatology, 56, 193–206.
Pereira, M. A., Clutton-Brock, T. H., & Kappeler, P. M. (2000). Understanding male primates. In Primate Males, ed. P. M. Kappeler. Cambridge: Cambridge University Press, pp. 271–7.
Plavcan, J. M. & van Schaik, C. P. (1992) Intrasexual competition and canine dimorphism in anthropoid primates. American Journal of Physical Anthropology, 87, 461–77.
Plavcan, J. M. & van Schaik, C. P.(1997). Intrasexual competition and body weight dimorphism in anthropoid primates. American Journal of Physical Anthropology, 103, 37–68.
Plavcan, J. M. (1990). Sexual dimorphism in the dentition of extant anthropoid primates. Ph.D. thesis, Duke University, Ann Arbor.
Plavcan, J. M.(1999). Mating systems, intrasexual competition and sexual dimorphism in primates. In Comparative Primate Socioecology, ed. P. C. Lee. Cambridge: Cambridge University Press, pp. 241–69.
Plavcan, J. M.(2000). Inferring social behavior from sexual dimorphism in the fossil record. Journal of Human Evolution, 39, 327–44.
Plavcan, J. M.(2001). Sexual dimorphism in primate evolution. Yearbook of Physical Anthropology, 44, 25–53.
Plavcan, J. M.(2003). Scaling relationships between craniofacial sexual dimorphism and body mass dimorphism in primates: implications for the fossil record. American Journal of Physical Anthropology, 120, 38–60.
Plavcan, J. M.(2004). Sexual selection, measures of sexual selection, and sexual dimorphism in primates. In Sexual Selection in Primates: A Comparative Perspective, ed. P. M. Kappeler & C. P. van Schaik. Cambridge: Cambridge University Press, pp. 230–52.
Plavcan, J. M., van Schaik, C. P., & Kappeler, P. M. (1995). Competition, coalitions and canine size in primates. Journal of Human Evolution, 28, 245–76.
Pope, B. (1966). Population characteristics of howler monkeys (Alouatta caraya) in northern Argentina. American Journal of Physical Anthropology, 24, 361–70.
Pope, B.(1968). Population characteristics. Biblio Primatology, 7, 13–70.
Poulsen, J. R., Clarke, C. J., & Smith, T. B. (2001). Seasonal variation in the feeding ecology of the gray-cheeked mangabey (Lophocebus albigena) in Cameroon. American Journal of Primatology, 54, 91–105.
Purvis, A. & Webster, A. J. (1999). Phylogenetically independent comparisons and primate phylogeny. In Comparative Primate Socioecology, ed. P. C. Lee. Cambridge: University of Cambridge Press, pp. 44–70.
Ravosa, M. J. (1998). Cranial allometry and geographic variation in slow lorises (Nycticebus). American Journal of Primatology, 45, 225–43.
Reed, C., O'Brein, T. G., & Kinnaird, M. E. (1997). Male social behavior and dominance hierarchy in the Sulawesi crested black macaque (Macaca nigra). International Journal of Primatology, 18, 247–60.
Remis, M. (1997). Western lowland gorillas (Gorilla gorilla gorilla) as seasonal frugivores: use of variable resources. American Journal of Primatology, 43, 87–109.
Rodriguez, M. A. R. (1985). Algunos aspectos sobre comportamiento, alimentacion y nivel de poblacion de los monos (Primates: Cebidae) en el Refugio De Fauna Silvestre Palo Verde (Guanacaste, Costa Rica). In Investigaciones Sobre Fauna Silvestr de Costa Rica. San Jose, Costa Rica: Editorial Universidad Estatal a Distancia, pp. 53–71.
Rose, M. D. (1977). Interspecific play between free ranging guerezas (Colobus guereza) and vervet monkeys (Cercopithecus aeithiops). Primates, 18, 957–64.
Rudran, R. (1979). The demography and social mobility of a red howler (Alouatta seniculus) population in Venezuela. In Vertebrate Ecology in the Northern Neotropics, ed. J. F. Eisenberg. Washington, DC: Smithsonian Institution Press, pp. 107–26.
Schlicte, H. (1978). A preliminary report on the habitat utilization of a group of howler monkeys (Alouatta villosa pigra) in the National Park of Tikal, Guatemala. In The Ecology of Arboreal Folivores, ed. G. G. Montgomery. Washington, DC: Smithsonian Institution Press, pp. 551–9.
Siex, K. S. & Struhsaker, T. T. (1999). Ecology of the Zanzibar red colobus monkey: demographic variability and habitat stability. International Journal of Primatology, 20, 163–92.
Silkiluwasha, F. (1981). The distribution and conservation status of the Zanzibar red colobus. African Journal of Ecology, 19, 187–94.
Silver, S. C., Ostro, L. E. T., Yeager, C. P., & Horwich, R. (1998). Feeding ecology of the black howler monkey (Alouatta pigra) in northern Belize. American Journal of Primatology, 45, 263–79.
Simmen, B. & Sabatier, D. (1996). Diets of some French Guianan primates: food composition and food choices. International Journal of Primatology, 17, 661–94.
Smith, C. C. (1977). Feeding behavior of social organization in howling monkeys. In Primate Ecology, ed. T. T. Clutton-Brock. London: Academic Press, pp. 97–126.
Smith, R. J. & Cheverud, J. M. (2002). Scaling of sexual dimorphism in body mass: a phylogenetic analysis of Rensch's rule in primates. International Journal of Primatology, 23, 1095–135.
Smith, R. J. & Jungers, W. L. (1997). Body mass in comparative primatology. Journal of Human Evolution, 32, 523–59.
Smith, R. J. (1999). Statistics of sexual size dimorphism. Journal of Human Evolution, 36, 423–59.
Southwick, C. H., Zhang, Y., Jiang, H., Liu, Z., & Qu, W. (1996). Population ecology of rhesus macaques in tropical and temperate habitats. In Evolution and Ecology of Macaque Societies, ed. J. E. Fa & D. G. Lindburg. Cambridge: Cambridge University Press, pp. 95–105.
Srivastava, A. & Dunbar, R. I. M. (1996). The mating system of hanuman langurs: a problem in optimal foraging. Behavioral Ecology and Sociobiology, 39, 219–26.
Stearns, S. C. & J. C. Koella (1986). The evolution of phenotypic plasticity in life-history traits: predictions of reaction norms for age and size at maturity. Evolution, 40, 893–915.
Stevenson, P. (1998). Proximal spacing between individuals in a group of woolly monkeys (Lagothrix lagothricha) in Tinigua National Park, Columbia. International Journal of Primatology, 19, 299–312.
Stevenson, P. R. (2000). Seed dispersal by woolly monkeys (Lagothrix lagothricha) at Tinigua National Park, Colombia: dispersal distance, germination rates, and dispersal quantity. American Journal of Primatology, 50, 275–89.
Stoner, K. E. (1996). Habitat selection and seasonal patterns of mantled howling monkeys (Alonatta palliata) in northeastern Costa Rica. International Journal of Primatology, 17, 1–30.
Strier, K. B. (2003). Demography and temporal scale of sexual selection. In Sexual Selection and Reproductive Competition in Primates: New Perspectives and Directions, Vol. 3, ed. C. B. Jones. Norman, OK: The American Society of Primatologists, pp. 45–63.
Struhsaker, T. T. & Leland, L. (1979). Socioecology of five sympatric monkey species in the Kibale Forest, Uganda. In Advances in the Study of Behavior, Vol. 9, ed. J. Roseblatt, R. A. Hinde, C. Beer, & M. C. Busnel. New York: Academic, pp. 158–228.
Struhsaker, T. T. & Leland, L.(1987). Colobines: infanticide by adult males. In Primate Societies, ed. B. B. Smuts, D. L. Cheney, R. M. Seyfarth, et al. Chicago: University of Chicago Press, pp. 83–97.
Struhsaker, T. T. (1975). The Red Colobus Monkey. Chicago: University of Chicago Press.
Suzuki, A. (1979). The variation and adaptation of social groups of chimpanzees and black and white colobus monkeys. In Primate Ecology and Human Origins, ed. I. S. Bernstein & E. O. Smith. New York: Garland STPM Press, pp. 153–73.
Thorington, R. W., Ruiz, J. C., & Eisenberg, J. F. (1984). A study of black howler monkey (Alouatta caraya) populations in northern Argentina. American Journal of Primatology, 6, 357–66.
Tilson, R. (1977). Social organization of Simakobu monkeys (Nasalis concolor) in Siberut Island, Indonesia. Journal of Mammalogy, 58, 202–12.
Turner, T. R., Anapol, F., & Jolly, C. J. (1997). Growth, development, and sexual dimorphism in vervet monkeys (Cercopithecus aethiops) at four sites in Kenya. American Journal of Physical Anthropology, 103, 19–35.
Tutin, C. E. G., Ham, R. M., White, L. J. T., & Harrison, M. J. S. (1997). The primate community of the Lope Reserve, Gabon: diets, responses to fruit scarcity, and effects on biomass. American Journal of Primatology, 42, 1–24.
Van Schaik, C. P. (2000). Social counterstrategies against male infanticide in primates and other mammals. In Primate Males, ed. P. M. Kappeler. Cambridge: Cambridge University Press, pp. 34–52.
Vogel, C. (1971). Behavioral differences of Presbytis entellus in two different habitats. In Proceedings of the Third International Congress of Primatology, Zurich 1970, ed. H. Kummer. Basel: S. Karger, pp. 41–7.
Wallace, R. B., Painter, R. L. E., & Taber, A. B. (1998). Primate diversity, habitat preferences, and population density estimates in Noel Kempff Mercado National Park, Santa Cruz Department, Bolivia. American Journal of Primatology, 46, 197–211.
Watanabe, K. (1981). Variation in group composition and population density of the two sympatric Mentawaian leaf monkeys. Primates, 22, 145–60.
Whitten, P. L. (1983). Diet and dominance among female vervet monkeys (Cercopithecus aethiops). American Journal of Primatology, 5, 139–59.
Wolf, K. (1978). Preliminary report on the completion of the field phase of a study of the social behavior of the silvered leaf monkeys (Presbytis cristata) at Kuala Selangor, Peninsular Malaysia. Kuala Lumpur: Department of Wildlife and National Parks.
Yamakoshi, G. (1998). Dietary responses to fruit scarcity of wild chimpanzees at Bossou, Guinea: possible importance of tool use. American Journal of Physical Anthropology, 106, 283–95.
Yeager, C. P. (1989). Feeding ecology of the proboscis monkey (Nasalis larvatus). International Journal of Primatology, 10, 497–530.
Yeager, C. P.(1991). Proboscis monkey (Nasalis larvatus) social organization: intergroup patterns of association. American Journal of Primatology, 23, 73–86.
Ziegler, T., Hodges, K., Winkler, P., & Hiestermann, M. (2000). Hormonal correlates of reproductive seasonality in wild female Hanuman langurs (Presbytis entellus). American Journal of Primatology, 51, 119–34.