Even adult sex ratios in lemurs: Potential costs and benefits of subordinate males in Verreaux's sifaka (Propithecus verreauxi) in the Kirindy Forest CFPF, Madagascar

American Journal of Physical Anthropology

Volumn 140, Issue 3, 2009, Pages 487-497

  Kappeler, Peter M ^a,b   Mass, Vanessa ^a,b   Port, Markus ^a,b  

^a GERMAN PRIMATE CENTER   (Germany)

^b UNIVERSITY OF GÖTTINGEN   (Germany)

Author keywords

Group composition; Mating skew; Operational sex ratio; Socio ecological theory

Indexed keywords

AGGRESSION; ANIMAL EXPERIMENT; ARTICLE; CONTROLLED STUDY; FEEDING BEHAVIOR; FEMALE; MADAGASCAR; MALE; MATING; NONHUMAN; POPULATION MIGRATION; POPULATION RESEARCH; PROPITHECUS VERREAUXI; PROSIMIAN; SEX DIFFERENCE; SEX RATIO; SURVIVAL RATE;

AGGRESSION; ANIMALS; ENVIRONMENT; FEMALE; LEMUR; MADAGASCAR; MALE; POPULATION DYNAMICS; SEX RATIO; SEXUAL BEHAVIOR, ANIMAL; SOCIAL BEHAVIOR; SOCIAL DOMINANCE; TREES;

LEMUR; LEMURIDAE; PROPITHECUS; PROPITHECUS VERREAUXI; STREPSIRHINI;

EID: 70349902257     PISSN: 00029483     EISSN: 10968644     Source Type: Journal    
DOI: 10.1002/ajpa.21091     Document Type: Article

References (135)

1. Alexander RD. 1974. The evolution of social behavior. Annu Rev Ecol Syst 5:325-383.
2. Altmann J. 1990. Primate males go where the females are. Anim Behav 39:193-195.
3. Andelmann SJ. 1986. Ecological and social determinants of cercopithecine mating patterns. In: Rubenstein DI, Wrangham RW, editors. Ecological aspects of social evolution: birds and mammals. Princeton: Princeton University Press. p 201-216.
4. Baldellou M, Henzi SP. 1992. Vigilance, predator detection and the presence of supernumerary males in vervet monkey troops. Anim Behav 43:451-461.
5. Balm PHM. 1999. Stress physiology in animals. Sheffield: Shef- field Academic Press.
6. Bateman AJ. 1948. Intra-sexual selection in Drosophila. Heredity 2:349-368.
7. Bayart F, Simmen B. 2005. Demography, range use, and behavior in black lemurs (Eulemur macaco macaco) at Ampasikely, northwest Madagascar. Am J Primatol 67:299-312.
8. Benadi G, Fichtel C, Kappeler PM. 2008. Intergroup relations and home range use in Verreaux's sifaka (Propithecus verreauxi). Am J Primatol 70:956-965.
9. Bertram BCR. 1978. Living in groups: predators and prey. In: Krebs JR, Davies NB, editors. Behavioural ecology: an evolutionary approach. Oxford: Blackwell Scientific. p 64-96.
10. Borries C, Launhardt K, Epplen C, Epplen JT, Winkler P. 1999. Males as infant protectors in Hanuman langurs (Presbytis entellus) living in multimale groups - defence pattern, paternity and sexual behaviour. Behav Ecol Sociobiol 46:350-356.
11. Brockman DK. 1994. Reproduction and mating systems of Verreaux's sifaka, Propithecus verreauxi, at Beza Mahafaly, Madagascar [PhD thesis]. New Haven, CT: Yale University.
12. Brockman DK. 1999. Reproductive behavior of female Propithecus verreauxi at Beza Mahafaly, Madagascar. Int J Primatol 20:375-398.
13. Brockman DK. 2003. Polyboroides radiatus predation attempts on Propithecus verreauxi. Folia Primatol 74:71-74.
14. Brockman DK, Whitten PL. 1996. Reproduction in free-ranging Propithecus verreauxi: estrus and the relationship between multiple partner matings and fertilization. Am J Phys Anthropol 100:57-69.
15. Brockman DK, Whitten PL, Richard AF, Benander B. 2001. Birth season testosterone levels in male Verreaux's sifaka, Propithecus verreauxi: insights into socio-demographic factors mediating seasonal testicular function. Behav Ecol Sociobiol 49:117-127.
16. Brockman DK, Whitten PL, Richard AF, Schneider A. 1998. Reproduction in free-ranging male Propithecus verreauxi: the hormonal correlates of mating and aggression. Am J Phys Anthropol 105:137-151.
17. Cant MA, English S. 2006. Stable group size in cooperative breeders: the role of inheritance and reproductive skew. Anim Behav 17:560-568.
18. Cheney DL. 1987. Interactions and relationships between groups. In: Smuts BB, Cheney DL, Seyfarth RM, Wrangham RW, Struhsaker TT, editors. Primate societies. Chicago: University of Chicago Press. p 267-281.
19. Cheney DL, Seyfarth RM. 1977. Behaviour of adult and immature male baboons during inter-group encounters. Nature 269:404-406.
20. Clutton-Brock TH. 1989. Mammalian mating systems. Proc R Soc Lond B 236:339-372.
21. Clutton-Brock TH, Guinness FE, Albon SD. 1982. Red deer: behavior and ecology of two sexes. Chicago: University of Chicago Press.
22. Clutton-Brock TH, Harvey PH. 1977. Primate ecology and social organisation. J Zool 183:1-39.
23. Clutton-Brock TH, Parker GA. 1995. Sexual coercion in animal societies. Anim Behav 49:1345-1365.
24. Clutton-Brock TH, Vincent ACJ. 1991. Sexual selection and the potential reproductive rates of males and females. Nature 351:58-60.
25. Constable J, Ashley M, Goodall J, Pusey A. 2001. Non-invasive paternity assignment in Gombe chimpanzees. Mol Ecol 10:1279-1300.
26. Cords M. 2000. The number of males in guenon groups. In: Kappeler PM, editor. Primate males: causes and consequences of variation in group composition. Cambridge: Cambridge University Press. p 84-96.
27. Davies NB. 1992. Dunnock behaviour and social evolution. Oxford: Oxford University Press.
28. Dobson AJ. 1990. An introduction to generalized linear models. London: Chapman and Hall.
29. Duffy KG, Wrangham RW, Silk JB. 2007. Male chimpanzees exchange political support for mating opportunities. Curr Biol 17:R586-R587.
30. Eisenberg JF. 1979. Habitat, economy, and society: some correlations and hypotheses for the Neotropical primates. In: Bernstein IS, Smith EO, editors. Primate ecology and human origins. New York: Garland Press. p 215-262.
31. Emlen ST, Oring LW. 1977. Ecology, sexual selection, and evolution of mating systems. Science 197:215-223.
32. Erhart EM, Overdorff DJ. 1998. Infanticide in Propithecus diadema edwardsi: an evaluation of the sexual selection hypothesis. Int J Primatol 19:73-81.
33. Fashing PJ. 2001. Male and female strategies during intergroup encounters in guerezas (Colobus guereza): evidence for resource defense mediated through males and a comparison with other primates. Behav Ecol Sociobiol 50:219-230.
34. Fichtel C, Kappeler PM. 2002. Anti-predator behavior of group-living Malagasy primates: mixed evidence for a referential alarm call system. Behav Ecol Sociobiol 51:262-275.
35. Fichtel C, Kraus C, Ganswindt A, Heistermann M. 2007. Influence of reproductive season and rank on fecal glucocorticoid levels in free-ranging male Verreaux's sifakas (Propithecus verreauxi). Horm Behav 51:640-648.
36. Gachot-Neveu H, Petit M, Roeder JJ. 1999. Paternity determination in two groups of Eulemur fulvus mayottensis: implications for understanding mating strategies. Int J Primatol 20:107-119.
37. Gaulin SJ, Sailer LD. 1985. Are females the ecological sex? Am Anthropol 87:111-119.
38. Goldizen AW. 1987. Facultative polyandry and the role of infant-carrying in wild saddle-back tamarins (Saguinus fuscicollis). Behav Ecol Sociobiol 20:99-109.
39. Goodman SM. 1994. The enigma of anipredator behavior in lemurs: evidence of a large extinct eagle on Madagascar. Int J Primatol 15:129-134.
40. Gould L. 1996a. Male-female affiliative relationships in naturally occuring ringtailed lemurs (Lemur catta) at the Beza-Mahafaly reserve, Madagascar. Am J Primatol 39:63-78. (Pubitemid 126522173)
41. Gould L. 1996b. Vigilance behavior during the birth and lactation season in naturally occuring ring-tailed lemurs (Lemur catta) at the Beza-Mahafaly Reserve, Madagascar. Int J Primatol 17:331-347.
42. Gould L, Fedigan LM, Rose LM. 1997. Why be vigilant? The case of the alpha animal. Int J Primatol 18:401-414.
43. Gould L, Ziegler T. 2007. Variation in fecal testosterone levels, inter-male aggression, dominance rank and age during mating and post-mating periods in wild adult male ring-tailed lemurs (Lemur catta). Am J Primatol 69:1325-1339.
44. Hamilton WD. 1971. Geometry for the selfish herd. J Theor Biol 31:295-311.
45. Hamilton WJ, Bulger J. 1992. Facultative expression of behavioral differences between one-male and multimale savanna baboon groups. Am J Primatol 28:61-71.
46. Harcourt A. 1987. Dominance and fertility among female primates. J Zool (Lond) 213:471-487.
47. Harcourt AH. 1978. Strategies of emigration and transfer by primates, with particular reference to gorillas. Z Tierpsychol 48:401-420.
48. Hill RA, Lee PC. 1998. Predation risk as an influence on group size in cercopithecoid primates: implications for social structure. J Zool (Lond) 245:447-456.
49. Hussmann S. 1996. Wachsamkeitsverhalten bei freilebenden Larvensifakas (Propithecus v. verreauxi Grandidier, 1867): Sind die Mannchen wachsamer als die Weibchen und kann dies als "Dienstleistung" gegenuber den Weibchen gedeutet werden? [MSc thesis]. Wurzburg: University of Wurzburg.
50. Ims RA. 1988. Spatial clumping of sexually receptive females induces space sharing among male voles. Nature 335:541-543.
51. Isbell LA. 1991. Contest and scramble competition: patterns of female aggression and ranging behaviour among primates. Behav Ecol Sociobiol 2:143-155.
52. Isbell LA, Young TP. 1993. Social and ecological influences on activity budgets of vervet monkeys, and their implications for group living. Behav Ecol Sociobiol 32:377-385.
53. Jamieson IG. 1997. Testing reproductive skew models in a communally breeding bird, the pukeko, Porphyrio porphyrio. Proc R Soc Lond B 264:335-340.
54. Janson CH. 1988. Intra-specific food competition and primate social structure: a synthesis. Behaviour 105:1-17.
55. Janson CH, Goldsmith L. 1995. Predicting group size in primates: foraging costs and predation risks. Behav Ecol Sociobiol 6:326-336.
56. Johnstone RA. 2000. Models of reproductive skew: a review and synthesis. Ethology 106:5-26.
57. Kappeler PM. 1991. Patterns of sexual dimorphism in body-weight among prosimian primates. Folia Primatol 57:132-146.
58. Kappeler PM. 1999. Primate socioecology: new insights from males. Naturwissenschaften 86:18-29.
59. Kappeler PM. 2000. Causes and consequences of unusual sex ratios among lemurs. In: Kappeler PM, editor. Primate males. Cambridge: Cambridge University Press. p 55-63.
60. Kappeler PM, Port M. 2008. Mutual tolerance or reproductive competition? Patterns of reproductive skew among male red-fronted lemurs (Eulemur fulvus rufus). Behav Ecol Sociobiol 62:1477-1488.
61. Kappeler PM, Schäffler L. 2008. The lemur syndrome unresolved: extreme male reproductive skew in sifakas (Propithecus verreauxi), a sexually monomorphic primate with female dominance. Behav Ecol Sociobiol 62:1007-1010.
62. Kappeler PM, van Schaik CP. 2002. Evolution of primate social systems. Int J Primatol 23:707-740.
63. Karpanty SM, Goodman S. 1999. Diet of the Madagascar harrier-hawk. Polyboroides radiatus, in Southeastern Madagascar. J Raptor Res 33:313-316.
64. Keller L, Reeve HK. 1994. Partitioning of reproduction in animal societies. Trends Ecol Evol 9:98-102.
65. Kitchen DM. 2004. Alpha male black howler monkey responses to loud calls: effect of numeric odds, male companion behaviour and reproductive investment. Anim Behav 67:125-139.
66. Koenig A. 1995. Group size, composition and reproductive success in wild common marmosets (Callithrix jacchus). Am J Primatol 35:311-317.
67. Koenig A. 2000. Competitive regimes in forest-dwelling hanuman langur females (Semnopithecus entellus). Behav Ecol Sociobiol 48:93-109. (Pubitemid 30597600)
68. Koenig A, Borries C. 2002. Feeding competition and infanticide constrain group size in wild hanuman langurs. Am J Primatol 57:33-34.
69. Kokko H, Johnstone RA. 1999. Social queuing in animal societies: a dynamic model of reproductive skew. Proc R Soc Lond B 266:571-578.
70. Kraus C, Heistermann M, Kappeler PM. 1999. Physiological suppression of sexual function of subordinate males: a subtle form of intrasexual competition among male sifakas (Propithecus verreauxi)? Physiol Behav 66:855-861. (Pubitemid 29281648)
71. Kubzdela KS. 1997. Sociodemography in diurnal primates: the effects of group size and female dominance rank on intragroup spatial distribution, feeding competition, female reproductive success, and female dispersal patterns in white sifaka, Propithecus verreauxi verreauxi [Doctoral thesis]. Chicago: University of Chicago.
72. Lewis RJ. 2004a. Male-female relationships in sifaka (Propithecus verreauxi verreauxi): power, conflict, and cooperation [PhD dissertation]. Durham, NC: Duke University.
73. Lewis RJ. 2004b. Stained v. clean males: female power maintains male bimorphism in Verreaux's sifaka (Propithecus verreauxi verreauxi). Am J Phys Anthropol Suppl 38:135.
74. Lewis RJ. 2008. Social influences on group membership in Propithecus verreauxi verreauxi. Int J Primatol 29:1249-1270.
75. Lewis RJ, Kappeler PM. 2005. Seasonality, body condition, and timing of reproduction in Propithecus verreauxi verreauxi in the Kirindy Forest. Am J Primatol 67:347-364.
76. Lewis RJ, Razafindrasamba SM, Tolojanahary JP. 2003. Observed infanticide in a seasonal breeding prosimian (Propithecus verreauxi verreauxi) in Kirindy Forest, Madagascar. Folia Primatol 74:101-103.
77. Lewis RJ, van Schaik CP. 2007. Bimorphism in male Verreaux's sifaka in the Kirindy forest of Madagascar. Int J Primatol 28:159-182.
78. Linklater WL. 2000. Adaptive explanations in socio-ecology: lessons from the Equidae. Biol Rev 75:1-20.
79. Majolo B, Ventura R, Koyama NF. 2005. Sex, rank and age differences in the Japanese macaque (Macaca fuscata yakui) participation in inter-group encounters. Ethology 111:455-468. (Pubitemid 40670090)
80. Mitani JC, GrosLouis J, Manson JH. 1996. Number of males in primate groups: comparative tests of competing hypotheses. Am J Primatol 38:315-332.
81. Munck A, Guyrne PM, Holbrook NJ. 1984. Physiological functions of glucocorticoids in stress and their relation to pharmacological actions. Endocr Rev 5:25-44.
82. Newton PN. 1986. Infanticide in an undisturbed forest population of Hanuman langurs, Presbytis entellus. Anim Behav 34:785-789.
83. Nunn CL. 1999. The number of males in primate social groups: a comparative test of the socioecological model. Behav Ecol Sociobiol 46:1-13.
84. Ortega J, Arita HT. 2002. Subordinate males in harem groups of Jamaican fruit-eating bats (Artibeus jamaicensis): satellites or sneaks? Ethology 108:1077-1091.
85. Ostner J, Kappeler PM. 2004. Male life history and the unusual adult sex ratios of redfronted lemur, Eulemur fulvus rufus, groups. Anim Behav 67:249-259. (Pubitemid 38272183)
86. Ostner J, Kappeler PM, Heistermann M. 2008. Androgen and glucocorticoid levels reflect seasonally occurring social challenges in male redfronted lemurs (Eulemur fulvus rufus). Behav Ecol Sociobiol 62:627-638.
87. Overdorff DJ, Merenlender AM, Talata P, Telo A, Forward ZA. 1999. Life history of Eulemur fulvus rufus from 1988-1998 in southeastern Madagascar. Am J Phys Anthropol 108:295-310. (Pubitemid 29124545)
88. Pereira ME. 1991. Asynchrony within estrous synchrony among ring-tailed lemurs (Primates: Lemuridae). Physiol Behav 49: 47-52.
89. Pereira ME, Kappeler PM. 1997. Divergent systems of agonistic behaviour in lemurid primates. Behaviour 134:225-274. (Pubitemid 127046607)
90. Pochron ST, Tucker WT, Wright PC. 2004. Demography, life history, and social structure in Propithecus diadema edwardsi from 1986-2000 in Ranomafana national park, Madagascar. Am J Phys Anthropol 125:61-72.
91. Pochron ST, Wright PC. 2003. Variability in adult group compositions of a prosimian primate. Behav Ecol Sociobiol 54:285-293.
92. Pope TR. 1990. The reproductive consequences of male cooperation in the red howler monkey: paternity exclusion in multimale and single male troops using genetic markers. Behav Ecol Sociobiol 27:439-446.
93. Pope TR. 2000. The evolution of male philopatry in neotropical primates. In: Kappeler PM, editor. Primate males: the causes and consequences of variation in group composition. Cambridge: Cambridge University Press. p 219-235.
94. Pulliam HR. 1973. On the advantages of flocking. J Theor Biol 38:419-422.
95. Pulliam HR, Caraco T. 1984. Living in groups: is there an optimal group size? In: Krebs JR, Davies NB, editors. Behavioural ecology: an evolutionary approach, 2nd ed. Oxford: Blackwell Scientific. p 122-147.
96. Putland DA, Goldizen AW. 1998. Territorial behaviour in the Tasmanian native hen: group and individual performance. Anim Behav 56:1455-1463.
97. Rasoloarison R. 1995. Predation on vertebrates in the Kirindy forest, Western Madagascar. Ecotropica 1:59-65.
98. Richard A. 1974. Intraspecific variation in social-organization and ecology of Propithecus verreauxi. Folia Primatol 22:178-207.
99. Richard A, Rakotomanga P, Schwartz M. 1993. Dispersal by Propithecus verreauxi at Beza Mahafaly, Madagascar: 1984-1991. Am J Primatol 30:1-20.
100. Richard AF. 1985. Social boundaries in a Malagasy prosimian, the sifaka (Propithecus verreauxi). Int J Primatol 6:553-568.
101. Richard AF. 1987. Malagasy prosimians: female dominance. In: Smuts BB, Cheney DL, Seyfarth RM, Wrangham RW, Struhsaker TT, editors. Primate societies. Chicago: University of Chicago Press. p 25-33.
102. Richard AF, Dewar RE, Schwartz M, Ratsirarson J. 2000. Mass change, environmental variability and female fertility in wild Propithecus verreauxi. J Hum Evol 39:381-391. (Pubitemid 30845221)
103. Richard AF, Dewar RE, Schwartz M, Ratsirarson J. 2002. Life in the slow lane? Demography and life histories of male and female sifaka (Propithecus verreauxi verreauxi). J Zool Lond 256:421-436. (Pubitemid 34294296)
104. Richard AF, Rakotomanga P, Schwartz M. 1991. Demography of Propithecus verreauxi at Beza Mahafaly, Madagascar: sex ratio, survival and fertility, 1984-1988. Am J Phys Anthropol 84:307-322.
105. Robbins MM. 1995. A demographic analysis of male life history and social structure of mountain gorillas. Behaviour 132:21-47.
106. Robinson JG. 1988. Group size in wedge-capped capuchin monkeys Cebus olivaceus and the reproductive success of males and females. Behav Ecol Sociobiol 23:187-197.
107. Rose LM. 1994. Benefits and costs of resident males to female in white-faced capuchins, Cebus capucinus. Am J Primatol 32:235-248.
108. Rose LM, Fedigan LM. 1995. Vigilance in white-faced capuchins, Cebus capucinus, in Costa Rica. Anim Behav 49:63-70.
109. Rubenstein DI, Wrangham RW. 1986. Ecological aspects of social evolution. Princeton: Princeton University Press.
110. Rümenap S. 1997. Ethno-Endokrinologie freilebender weiblicher Kronensifakas (Propithecus verreauxi verreauxi, Grandidier 1867) in der Paarungszeit, unter besonderer Berücksichtigung altersspezifischer Unterschiede. Göttingen: Universität Göttingen.
111. Ryan SJ, Starks PT, Milton K, Getz WM. 2008. Intersexual conflict and group size in Alouatta palliata: a 23-year evaluation. Int J Primatol 29:405-420.
112. Sauther ML, Sussman RW. 1993. A new interpretation of the social organization and mating system of the ring-tailed lemur, Lemur catta. In: Kappeler PM, Ganzhorn JU, editors. Lemur social systems and their ecological basis. New York: Plenum. p 111-122.
113. Say L, Pontier D, Natoli E. 2001. Influence of oestrus synchronization on male reproductive success in the domestic cat (Felis catus L.). Proc R Soc Lond B 268:1049-1053.
114. Sorg J, Ganzhorn JU, Kappeler PM. 2003. Forestry and research in the Kirindy Forest/Centre de Formation Professionnelle Forestière. In: Goodman S, Benstead J, editors. The natural history of Madagascar. Chicago: University of Chicago Press. p 1512-1519.
115. Strier KB. 1994. Myth of the typical primate. Yearb Phys Anthropol 37:233-271.
116. Strum SC, Fedigan LM. 2000. Changing views of primate society: a situated North American view. In: Strum SC, Fedigan LM, editors. Primate encounters: models of science, gender, and society. Chicago: Chicago University Press. p 1-49.
117. Sussman RW, Garber PA. 1987. A new interpretation of the social organization and mating system of the Callithrichidae. Int J Primatol 8:73-92.
118. Takahata Y, Koyama N, Ichino S, Miyamoto N, Nakamichi M. 2006. Influences of group size on reproductive success of female ring-tailed lemurs: distinguishing between IGFC and PFC hypotheses. Primates 47:383-387.
119. Treves A. 1998. Primate social systems: conspecific threat and coercion-defense hypotheses. Folia Primatol 69:81-88. (Pubitemid 128485736)
120. Treves A. 2000. Prevention of infanticide: the perspective of infant primates. In: van Schaik CP, Janson CH, editors. Infanticide by males and its implications. Cambridge: Cambridge University Press. p 223-238.
121. Treves A. 2001. Reproductive consequences of variation in the composition of howler monkey (Alouatta spp.) groups. Behav Ecol Sociobiol 50:61-71. (Pubitemid 32592855)
122. Trivers RL. 1972. Parental investment and sexual selection. In: Campbell B, editor. Sexual selection and the descent of man. Chicago: Aldine. p 136-179.
123. van Hooff JARAM. 2000. Relationships among non-human primate males: a deductive framework. In: Kappeler PM, editor. Primate males: causes and consequences of variation in group composition. Cambridge: Cambridge University Press. p 183-191.
124. van Schaik CP. 1996. Social evolution in primates: the role of ecological factors and male behaviour. Proc Br Acad 88:9-31.
125. van Schaik CP. 2000. Social counterstrategies against infanticide by males in primates and other mammals. In: Kappeler PM, editor. Primate males: causes and consequences of variation in group composition. Cambridge: Cambridge University Press. p 34-52.
126. van Schaik CP, Assink PR, Salafsky N. 1992. Territorial behavior in southeast Asian langurs: resource defense or mate defense? Am J Primatol 26:233-242.
127. van Schaik CP, Hörstermann M. 1994. Predation risk and the number of adult males in a primate group: a comparative test. Behav Ecol Sociobiol 35:261-271. (Pubitemid 2142711)
128. van Schaik CP, Kappeler PM. 1996. The soical systems of gregarious lemurs: lack of convergence with anthropoids due to evolutionary disequilibrium? Ethology 102:915-941.
129. van Schaik CP, van Hooff JARAM. 1983. On the ultimate causes of primate social systems. Behaviour 85:91-117.
130. van Schaik CP, van Noordwijk MA. 1989. The special role of male Cebus monkeys in predation avoidance and its effect on group composition. Behav Ecol Sociobiol 24:265-276.
131. Vehrencamp SL. 1983. A model for the evolution of despotic versus egalitarian societies. Anim Behav 31:667-682.
132. Wolff JO, Macdonald DW. 2004. Promiscuous females protect their offspring. Trends Ecol Evol 19:127-134.
133. Wrangham RW. 1980. An ecological model of female-bonded primate groups. Behaviour 75:262-300.
134. Wright PC. 1999. Lemur traits and Madagascar ecology: coping with an island environment. Yearb Phys Anthropol 42:31-72.
135. Wright PC, Hecksher SK, Dunham A. 1997. Predation on Milne Edward's sifaka (Propithecus diadema edwardsi) by the fossa (Cryptoprocta ferox) in the rainforest of southeastern Madagascar. Folia Primatol 68:34-43. (Pubitemid 127478434)