Biological Exuberance: Animal Homosexuality and Natural Diversity

and captivity among Savanna (Olive) Baboons; unfortunately, mounting (and other sexual-behavior) rates between males in the wild could not be compared to rates in captivity because males were too aggressive to be kept together in captivity. On a related point, Rasa (1979b:321) found no substantial differences in Dwarf Mongoose same-sex (and opposite-sex) mounting rates when their behavior in crowded versus noncrowded captive conditions was compared (based on controlled observational regimes). Likewise, Heg and van Treuren (1998:689–90) did not find significantly higher rates of homosexual bonding (in the form of bisexual trios) when population densities increased among wild Oystercatchers.

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Bottlenose Dolphin (McBride and Hebb 1948:114, 122; Wells et al. 1987; Wells 1991; Wells et al. 1998:65- 67); Gorilla (Schaller 1963:278: Stewart 1977; Yamagiwa 1987a,b; Harcourt 1988; Porton and White 1996:723- 24).

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Jackdaw (Lorenz 1935/1970; Roell 1979); Elephants (Rosse 1892; Shelton 1965); Crested Black Macaque (Poirier 1964:147; Dixson 1977; Reed et al. 1997); Orange-fronted Parakeet (Buchanan 1966); Lion (Cooper 1942; Chavan 1981); Great Cormorant (Kortlandt 1949; Fukuda 1992); Regent Bowerbird (Phillipps 1905; Lenz 1994); Dolphins (Brown et al. 1966; Herzing and Johnson 1997). Similar erroneous assertions are sometimes made regarding transgender. Payne (1984:14), for example, claims that female-plumaged or transvestite male Ruffs occur only in captivity (citing Stonor 1937). In fact, female-plumaged males—generally referred to in this species as naked-nape males—are now known to be a regular feature of wild Ruff populations (cf. van Rhijn 1991) and have been discussed as such in the scientific literature since at least Hogan-Warburg (1966). Payne, R. B. (1984) Sexual Selection, Lek and Arcna Behavior, and Sexual Size Dimorphism in Birds, Ornithological Mongraphs no. 33 (Washington, D.C.: American Ornithologists’ Union).

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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 (Cezilly 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 (Schurmann 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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Pied Kingfisher (Reyer et al. 1986:216); Orang-utan (Kingsley 1982:227); Spotted Hyena (Frank 1996; Frank et al. 1985, 1995 ; Glickman et al. 1993); Western Gull (Wingfield et al. 1982). See also Mloszewski (1983:186), who indicates that masculinized female African Buffalo—i.e., those with “pronounced male secondary sexual characteristics,” likely due in part to a differing hormonal profile—do not participate in homosexual activity any more often than do nontransgendered females (and perhaps do so even less often). For other species in which a subset of individuals have different hormone profiles (not associated with homosexual activity), see Solomon, N. G., and J. A. French, eds. (1997) Cooperative Breeding in Mammals, pp. 241, 304–5, 370 (Cambridge: Cambridge University Press).

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Takhi (Boyd 1986:660). Although detailed hormonal studies of Takhi during pregnancy have been conducted, they did not involve sampling of androgens or other male hormones; see Monfort et al. 1994; Monfort, S. L., N. P. Arthur, and D. E. Wildt (1991) “Monitoring Ovarian Function and Pregnancy by Evaluating Excretion of Urinary Oestrogen Conjugates in Semi-Free-Ranging Przewalski’s Horses (Equus przewalskii),”