Biological Exuberance: Animal Homosexuality and Natural Diversity

In this regard, homosexual activity in some species is also claimed to be “caused” by unusual or abnormal environmental or climatic conditions, such as severe winter snowstorms that disrupt “normal” pairing in Golden Plovers (Nethersole-Thompson and Nethersole-Thompson 1961:207–8), or exceptionally rainy seasons that somehow “overstimulate” Ostriches (Sauer 1972:717) Assuming that ecological factors of this sort could be involved (which is debatable), an equally valid interpretation is that such species possess an inherent flexibility in their social and sexual systems that manifests itself during times of ecological flux or stress. Rather than being the “product” of “abnormal” conditions, then, such behavioral plasticity allows the species to respond “creatively”—in ways that, obviously, are not yet fully understood—to the vagaries of an ever-changing environment. See chapter 6 for further discussion.

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Cheetah (Herdman 1972:112, 123;Caro 1993:27–28, 1994:362; Ruiz-Miranda et al. 1998:1, 13). For more on the false dichotomy of “wild” versus “captive” studies of animals, and the general compatibility and continuity between the two, see de Waal 1989a:27-33, 1997:11 (Bonobo).

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Boto (Best and da Silva 1989:12-13); Orang-utan (van Schaik, C. P., E.A. Fox, and A. F. Sitompul [1996] “Manufacture and Use of Tools in Wild Sumatran Orangutans: Implications for Human Evolution,” Naturwissenschaften 83:186-88); Savanna (Olive) Baboon (DeVore, 1. [1965] “Male Dominance and Mating Behavior in Baboons,” p. 286, in F. A. Beach, ed., Sex and Behavior, pp. 266-89 [New York: John Wiley and Sons]); Thomson’s Gazelle (Walther 1995:30-31); King Penguin (Gillespie 1932; Stonehouse 1960); Black-headed Gull (Kharitonov and Zubakin 1984:103; van Rhijn and Groothuis 1987:144); Flamingo (Cézilly and Johnson 1995).

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Griffon Vulture (Blanco and Martinez 1996:247; Sarrazin et al. 1996:316); King Penguin (Weimerskirch et al. 1992:108); Gentoo Penguin (Williams and Rodwell 1992:637; Bost and Jouventin 1991:14); Flamingo (A. R. Johnson, personal communication); Dugong (Anderson 1997:440, 458; Preen 1989:384). See also chapter 3 for further discussion of heterosexual bias in the methods of sex determination employed during field studies of these and other species.

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Canids (Macdonald 1980, 1996); Macaques (Oi 1990a; Reed et al. 1997); Gibbons (Fox 1977; Edwards and Todd 1991); Rose 1992:1-2 (Killer Whale); Aperea (Rood 1972:42); Rufous Bettong (Johnson 1980:347).

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Orang-utan (Schürmann 1982:270-71, 282); Oystercatcher (Angier, N. [1998] “Birds’ Design for Living Offers Clues to Polygamy,” New York Times March 3, pp. B11–12).

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van Lawick-Goodall, J. (1970) “Tool-Using in Primates and Other Vertebrates,” p. 208, Advances in the Study of Behavior 3:195-249.

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Sage Grouse (Scott 1942:495); Rhesus Macaque (Carpenter 1942:150); Fat-tailed Dunnart (Ewer 1968:351); Long-eared Hedgehog (Poduschka 1981:84); Takhi (Boyd 1986:660).

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Common Garter Snake (Noble 1937:710–11); Hooded Warbler (Niven 1993:192).

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African Elephant (Sikes 1971:265–66); Snow/Canada Goose (Starkey 1972:456–57).

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Western Gull (Wingfield et al. 1982); Ring-billed Gull (Kovacs and Ryder 1985). See also the examples of more “intense” nesting behavior in female pairs of Ring Doves and Budgerigars discussed in note 15, chapter 1, which might also be correlated with hormonal effects.

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For a summary of these results, see Vasey, P. L. (1995) “Homosexual Behavior in Primates: A Review of Evidence and Theory,” International Journal of Primatology 16:173–204. Some of the species in which hormone levels have been studied in association with homosexual behavior are Rhesus Macaques (Akers and Conaway 1979; Turner et al. 1989) and Hanuman Langurs (Srivastava et al. 1991). (Turner, J. J., J. G. Herndon, M.-C. Ruiz de Elvira, and D. C. Collins [1989] “A Ten-Month Study of Endogenous Testosterone Levels and Behavior in Outdoor-Living Female Rhesus Monkeys [Macaca mulatta],” Primates 30:523–30.) For a discussion of the problematic nature of studies on laboratory rats that purport to show an association between homosexual behavior and hormones, see Mondimore, F. M. (1996) A Natural History of Homosexuality, pp. 111–13, 129–30 (Baltimore: Johns Hopkins University Press); Byne, W. (1994) “The Biological Evidence Challenged,” Scientific American 270(5):50–55.

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