Biological Exuberance: Animal Homosexuality and Natural Diversity

Crested Black Macaque (Dixson 1977:70—71); Bottlenose Dolphin (Ostman 1991:313; Dudok van Heel and Mettivier 1974:12; Saayman and Tayler 1973); Spinner Dolphin (Norris and Dohl 1980a:845; Norris et al. 1994:199); Common Murre (Birkhead 1978a:326); Blue-bellied Roller (Moynihan 1990).

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Rhesus Macaque (see, for example, Sade 1968:32-33); Japanese Macaque (Hanby 1974:843, 845; Wolfe, “Human Evolution and the Sexual Behavior of Female Primates,” p. 129).

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For further discussion see chapter 5. On a related point, aggressive behaviors may accompany homosexual interactions in some species and are therefore used to argue that such behavior is not “really” sexual. However, aggression is also characteristic of heterosexual relations in many species, where such male-female interactions are still classified as “sexual.”

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Kob (Buechner and Schloeth 1965:218); Giraffe (Pratt and Anderson 1985:774-75); northern jacana (del Hoyo, J., A. Elliott, and J. Sargatal, eds. [1996] Handbook of the Birds of the World, vol. 3: Hoatzin to Auks, p. 282. [Barcelona: Lynx Edicións]); Orang-utan (Galdikas 1981:286).

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Walrus (Dittrich 1987:168); Musk-ox (Smith 1976:62); Bighorn Sheep (Hogg 1984:527; Geist 1971:139); Asiatic Mouflon (McClelland 1991:81); Grizzly Bear (Craighead et al. 1995:161); Olympic Marmot (Barash 1973:212); White-tailed Deer (Hirth 1977:43); Orang-utan (Galdikas 1981:286); White-faced Capuchin (Manson et al. 1997:775); Northern Fur Seal (Gentry 1998:172); Ruff (Hogan-Warburg 1966:167-68). Additionally, in one study of Matschie’s Tree Kangaroos—a species in which researchers deny that mounting between females is (homo)sexual (J. Steenberg, personal communication)—all mounts observed between animals of the opposite sex were “incomplete” in that they did not involve penetration or thrusting (Hutchins et al. 1991:158). Another study of the same population found both that “full” copulations between males and females were infrequent, and that in heterosexual contexts females showed few overt signs of sexual interest, since the behavioral cues for female sexual arousal are extremely subtle (Dabek 1994:84, 93—94, 116).

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Morrill and Robertson 1990 (Tree Swallow); Scott, M. P., and T. N. Tan (1985) “A Radiotracer Technique for the Determination of Male Mating Success in Natural Populations,” Behavioral Ecology and Sociobiology 17:29-33. More recently, a copulation-verification technique using fluorescent powder has been tested for rodents. Dusted on males, the powder is transferred to females during mating and can be checked using ultraviolet light. Ironically, during the testing of this procedure, pairs of females were used as “controls” since it was assumed that they would not engage in mounting behavior with one another. Nevertheless, 12 percent of female pairs showed transfer of powder—but of course this was interpreted by researchers as evidence of nonsexual contact between such females (Ebensperger, L. A., and R. H. Tamarin [1997] “Use of Fluorescent Powder to Infer Mating Activity of Male Rodents,” Journal of Mammalogy 78:888-93).

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Rhesus Macaque (Erwin and Maple 1976); field report of penetration and ejaculation (Sade 1968:27); see also Kempf (1917:134) for an even earlier documentation of anal penetration between (captive) male Rhesus Macaques. Walther (1990:308) makes a parallel claim that mounting activity between male hoofed mammals does not constitute (homo)sexual behavior because erection and anal penetration are not always observed (Walther, “Bovids: Introduction”). On a related point, Tuttle (1986:289) takes great pains to point out that rump-rubbing and mounting between male Bonobos do not “qualify” as genital contact because, “pace certain sodomites, the anus is not a genital organ (International Anatomical Nomenclature Commitee, 1977, p. A49).” Tuttle does, however, accept that sexual activity between females—which he calls “bizarre homosexual hunching” (ibid., p. 282)—qualifies as genital contact (Tuttle, R. H. [1986] Apes of the World: Their Social Behavior, Communication, Mentality, and Ecology [Park Ridge, N.J.: Noyes Publications]). For a recent survey of homosexual behavior in primates that (wisely) drops the occurrence of penetration, arousal, and/or orgasm as a defining criterion of the behavior, see Vasey, “Homosexual Behavior in Primates,” p. 175.

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On a similar gradation of mounting behavior in male birds, see Moynihan 1955:105 (Black-headed Gull).

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