Biological Exuberance: Animal Homosexuality and Natural Diversity

Bonobo, wild (Kano 1992:187 [table 24], 140; Kitamura 1989:53, 55-57, 61); Bonobo, captive (de Waal 1995:41 [table 3.1]); Black Swan (Braithwaite 1981:141-42). Five other species for which the relevant quantitative information is available are Pig-tailed, Crested Black, and Stumptail Macaques, Common Chimpanzees, and Vervets. Although the wild (or semi-wild) and captive figures in these cases are more difficult to compare (due to differences in group size and composition, observed behaviors, length of study periods, etc.), they also generally show fairly comparable rates. For Pig-tailed Macaques in the wild, 7-23 percent of mounting is same-sex, compared to about 25 percent in captivity (rates in the wild based on information in Oi 1990a:350—1 [including table [V], Oi 1996:345, and Bernstein 1967:226-27; captivity—Tokuda et al. 1968:287, 291 [table 7]). Among captive Crested Black Macaques, about 5 percent of mounting is between males (Dixson 1977:74, 77), compared to an estimated 8 percent in the wild (C. Reed, personal communication; figures for both of these species combine “copulatory” with “noncopulatory” mounts). However, another study (Bernstein 1970:94 [table IV]) yielded a much higher rate of same-sex mountings in captivity for these species—49 percent for Pigtails, 22 percent for Crested Blacks—demonstrating that there can be considerable differences between individual studies and/or populations (see also Bernstein [1967:228] for more on wild/captive comparisons in Pigtails). In Stumptail Macaques, 25 percent of sexual interactions (of all types) in captivity are homosexual (Chevalier-Skolnikoff 1974:100-101, 110), compared to 30-40 percent for mounting in a semi-wild troop (formerly captive animals that were transplanted and released) (Estrada et al. 1977:667 [fig.14]; Estrada and Estrada 1978:672 [table 4]). In Common Chimpanzees, same-sex mounting actually occurs more frequently in the wild: de Waal and van Hooff (1981:182 [table 2]) found that mounting between males in captivity constitutes only 1-2 percent of the behaviors involved in reassurance, enlistment of support, and other activities during conflicts, while Nishida and Hosaka (1996:120-21 [tables 9.5-9.6]) found that mounting accounts for one-third to one-half of such behaviors in wild Chimps. Likewise, Bernstein (1970:94 [table IV]) found that 9 percent of mounting activity in captive Vervets is same-sex, while Gartlan (1969:144, 146) and Struhsaker (1957:21, 27 [tables 8, 10]) both recorded 11 percent same-sex mounting in the wild. Rowell (1967b) also conducted a detailed quantitative comparison of behavioral frequency rates in the wild 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; Röell 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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