Bruce Bagemihl - Biological Exuberance

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Examples of species in which homosexual activity is given only cursory treatment compared to heterosexual activity are too numerous to list, but include White-tailed Deer (Hirth 1977), Wapiti (Harper et al. 1967), Fat-tailed Dunnart (Ewer 1968), Matschie’s Tree Kangaroo (Hutchins et al. 1991), Wattled Starling (Sontag 1991), Sage Grouse (Wiley 1973, Gibson and Bradbury 1986), and Canary-winged Parakeet (Arrowood 1988). In a few studies, however, detailed quantitative and descriptive information is provided on homosexual behavior; see, for example, Kitamura 1989, Kano 1992, de Waal 1987, 1995, 1997 (Bonobo); Edwards and Todd 1991 (White-handed Gibbon); Hanby 1974, Eaton 1978, Chapais and Mignault 1991, Vasey 1996 (Japanese Macaque); Pratt and Anderson 1985 (Giraffe); Jamieson and Craig 1987a (Pukeko); van Rhijn and Groothuis 1985, 1987 (Black-headed Gull); Rogers and McCulloch 1981 (Galah). For further discussion of how same-sex activity has frequently not been considered “genuine” sexual behavior, see the next section.

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Spinner Dolphin (Wells 1984:468; Bateson 1974); Kob (Buechner and Schloeth 1965:219 [table 21]); Crested Black Macaque (Dixson 1977); Brown Capuchin (Linn et al. 1995); Giraffe (Dagg and Foster 1976:75—77).

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Western Gull (Hunt et al. 1984:160) (see Hayward and Fry [1993:16, 18] for a recent reiteration of the findings of this study, in which sexual activity is once again downplayed); Black-crowned Night Heron (Noble et al. 1938:28-29); on comparable levels of crowding in wild colonies, see Gross 1923:13—15; Davis 1993:6; Kazantzidis et al. 1997:512); Laughing Gull (Hand 1985:128); Canary-winged Parakeet (Arrowood 1988. 1991); Greater Rhea (Fernández and Reboreda 1998:341); Zebra Finch (Burley 1981:722).

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Gorilla (Harcourt 1979a:255). Harcourt et al. (1981:266) also characterize heterosexual copulation as “rare.” In addition, they report directly observing only 69 episodes of heterosexual mating (other copulations were heard but not seen) compared to 10 episodes between females, which yields an even higher proportion of nearly 13 percent homosexual activity.

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Western Gull (Hunt et al 1980:474); Spotted Hyena (Glickman 1993; Burr 1996:118-19); for further discussion of comparisons between wild and captive animals, see the next chapter

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Tree Swallow (M. P. Lombardo, personal communication: Venier et al. 1993:413; Lombardo 1986; Leffelaar and Robertson 1984:78). Similarly, homosexual mounting is claimed to be very rare in Northern Fur Seals, yet most heterosexual matings in this species are missed by observers because they occur at night (Gentry 1998:75—77, 107, 145).

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For specific examples, see Nilgiri Langur (Poirier 1970; Hohmann 1989). White tailed Deer (Hirth 1977: Rue 1989), Mule Deer (Geist 1981; Halford et al. 1987; Wong and Parker 1988), Red Deer (Lincoln et al. 1970; Guiness et al. 1971; Hall 1983), American Bison (McHugh 1958: Lott 1983 and personal communication), Red Squirrel (Layne 1954; Smith 1968; Ferron 1980), Mallard Duck Ramsey 1956; Lebret 1961; Schutz 1965; Bossema and Roemers 1985; Geh 1987), Ruff (Selous 1906—7; Bogan-Warburg 1966; Scheufler and Stiefel 1985; van Rhijn 1991), Oystercatcher (Makkink 1942; Heg and van Treuren 1998), Hooded Warbler (Niven 1994 and personal communication), Cliff Swallow (Emlen 1954, Barlow et al. 1963; Brown and Brown 1996), Red-backed Shrike (Owen 1946; Ashby 1958; Pounds 1972), Victoria’s Riflebird (Bourke and Austin 1947; Frith and Cooper 1996; C. B. Frith, personal communication), Sage Grouse (Scott 1942; Patterson 1952; Wiley 1973; Gibson and Bradbury 1986), Acorn Woodpecker (MacRoberts and MacRoberts 1976; Troetschler 1976; W. D. Koenig, personal communication), Gentoo Penguin (Robert 1934; Wheater 1976; Stevenson 1983), and the examples of wild versus captive observations in notes 99-100, chapter 4.

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Pukeko (Craig 1980:594; Jamieson and Craig 1987a;1252); Blak-headed Gull (van Rhijn and Groothuis 1985:161, 165).

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For example, Vasey (“Homosexual Behavior in Primates,” p. 181) sets up a general frequency scale in which homosexual behavior is classified as “rare” if it occurs “5 percent or less frequently as heterosexual behavior” and “occasional” if it occurs “6—24 percent as frequently as heterosexual behavior”; it is regarded as “frequent” only if it occurs “25 percent or more frequently.”Certainly this scale is to be commended for its standardization and multipoint assessment criteria (which also include nonquantitative measures); yet (like most scales) it is not without arbitrarines, and it is at odds with the heterosexual “5 percent” criterion. The “Polygyny threshold” model, which recognizes a frequency of ≥5 percent as significant for “minority” heterosexual mating systems (i.e., polygamy in otherweise monogamous species) was originally proposed by Verner, J., and M. P. Willson (1966) “The Influence of Habitats on Mating Systems of North American Passerine Birds,” Ecology 47:143-47. The 5 percent threshold continues to be widely used as a criterion for “regular” polygyny—for more recent examples, see Quinney 1983 (Tree Swallow); Moller, A. P. (1986) “Mating Systems Among European Passerines. A Review,” Ibis 128:234—50; Petit, L. J. (1991) “Experimentally Induced Polygyny in a Monogamous Bird Species: Prothonotary Warblers and the Polygyny Threshold,” Behavioral Ecology and Sociobiology 29:177—87.

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House Sparrow/Cowbird (Griffin 1959); Savanna Baboon (Marais 1922/1969:214-18); Kestrel (Olsen 1985). Regarding the House Sparrow/Cowbird case, a number of subsequent researchers (e.g., Selander and LaRue 1961; Rothstein 1980) have also interpreted this behavior as “aggression” or “appeasement.” Aside from the fact that the activity involving homosexual mounting is not identical to strictly “aggressive” or “preening invitation” displays in Cowbirds (cf. Laskey 1950), a “nonsexual” interpretation cannot explain why Cowbirds “tolerate” homosexual mountings from Sparrows and even actively solicit them. Moreover, the function(s) of these “head-down” displays remain controversial and speculative independent of any homosexual activity (cf. Scott and Grumstrup-Scott 1983). Specific arguments against an “aggressive” or “appeasement” interpretation of these types of behaviors (regardless of whether any same-sex mounting is involved) are presented in Verbeek, N. A. M., R. W. Butler, and H. Richardson (1981) “Interspecific Allopreening Solicitation in Female Brewer’s Blackbirds,” Condor 83:179—80. A parallel example involves Stonor (1937:88), who “reinterprets” Selous’s (1906—7) early descriptions of homosexual mountings by female Ruffs as involving heterosexual activity by “female-plumaged” males. More recent observers (e.g., Hogan-Warburg 1966, van Rhijn 1991) have corroborated Selous’s original observations, confirming not only the existence of both female and male homosexual activity, but also “female plumaged” males (i,e., the so-called naked-nape males) that participate in homosexuality.

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Chaffinch (Marjakangas 1981); Regent Bowerbird (Phillipps 1905; Marshall 1954). Similarly, early reports of courtship activity between male Swallow-tailed Manakins by Sick (1959, 1967) were discounted by Foster (1981:174), who tried to claim that the younger male birds being courted by adult males were actually females that had malelike plumage or were male observers or participants in nonsexual aggressive displays. However, Sick (1959:286) verified the male sex of these birds by dissecting them, and he stated explicitly (Sick 1967:17) that no aggression was involved in the displays. Moreover, it is clear from his descriptions (Sick 1959:286) that the display type that Foster (1981) claimed was aggressive occurs in the absence of younger males, not in their presence. Foster’s categorization of such displays as aggressive also appears to be based primarily on the fact that they occur between males, rather than on any inherent differences in the behaviors: as Foster (1981:172; 1984:58) admits, such displays are “extremely similar to” and “strongly reminiscent” of courtship behaviors. That Foster was unable to directly observe courtship displays of the type that Sick reported between males may also be due to geographic or subspecies differences in behaviors: Sick studied a population in Brazil while Foster observed birds in Paraguay. Other elements of the courtship displays between the two populations do appear to differ significantly, such as the vocalizations used and the direction in which males fly during the display (in Brazil, the male farthest from the courted bird begins the courtship “wheel,” while in Paraguay the bird closest to the courted bird begins). It should also be pointed out that Snow (1963) independently observed courtship between males in the closely related Blue-backed Manakin.