Biological Exuberance: Animal Homosexuality and Natural Diversity

“Preference” for same-sex activity is, admittedly, a rather elusive concept to measure when dealing with nonhumans (though not nearly as slippery as “identity”). Although we cannot access their internal motivations or “desires,” animals do offer a number of other clues as to their individual “preferences” in addition to the proportion of their behaviors or partners that are same-sex. These include homosexual activity being performed in (spite of) the presence of members of the opposite sex, individuals actively competing for the attentions of same-sex partners (rather than “resorting” to such activity), advances of opposite-sex partners being ignored and/or refused, and “widowed” or “divorced” individuals continuing to pair with same-sex partners after the loss of a homosexual mate (even when opposite-sex partners are available). These types of behaviors have in fact been reported in more than 50 mammals and birds (see the profiles for some examples), indicating that for at least some individuals in these species, same-sex activity has “priority” over opposite-sex activity in some contexts. The converse is also true for species such as Canada Geese, Silver Gulls, Bicolored Antbirds, Jackdaws, and Galahs: in situations where opposite-sex partners are not available, only a fraction of the population engages in same-sex activity, indicating more of a heterosexual “preference” in the remainder of the population.²⁴ Animals who do participate in same-sex activity in such a situational context could perhaps be said to exhibit a “latent” bisexuality; i.e., a predominantly heterosexual orientation with the potential to relate homosexually under certain circumstances. Another factor to be considered when evaluating individual “preferences” or degrees of bisexuality is the consensuality of the sexual interaction. Female Canada Geese and Silver Gulls in homosexual pairs, for example, may engage in occasional heterosexual copulations under duress; i.e., they are sometimes forcibly mated or raped by males. Likewise, heterosexually paired males in Common Murres, Laysan Albatrosses, Cliff Swallows, and several Gull species may be forcibly mounted by other males. Technically, all such individuals are “bisexual” because they engage in both homosexual and heterosexual activity, but the sort of bisexuality they exhibit is far different from that of a female Bonobo or a male Walrus, for instance, who willingly mates with animals of both sexes.

Broad patterns of sexual orientation across individuals show almost as much variation as that within individuals. In some species, the majority of animals are exclusively heterosexual, but a small proportion engage in bisexual activities (e.g., Mule Deer) or exclusively homosexual activities (e.g., male Ostriches). In others, the vast majority of individuals are bisexual and few if any are exclusively heterosexual or homosexual (e.g., Bonobos). Other species combine a pattern of nearly universal bisexuality with some exclusive homosexuality (e.g., male Mountain Sheep). In still other cases, the proportions are more equally distributed, but still vary considerably. In Silver Gulls, for instance, 10 percent of females are exclusively homosexual during their lives, 11 percent are bisexual, and 79 percent are heterosexual. Homosexual-bisexual-heterosexual splits for specific populations of other species include: 22-15-63 percent for Black-headed Gulls; 9-56-35 percent for Japanese Macaques; and 44-11-44 percent for Galahs.²⁵

Thus, sexual orientation has multiple dimensions—social, behavioral, chronological, and individual—which must all be taken into account when assessing patterns of heterosexual and homosexual involvement. It is true that exclusive homosexuality in animals is less common than bisexuality—but it is not a uniquely human phenomenon, for it occurs in many more species than previously supposed. Moreover, because of the wide prevalence of bisexuality—both within and across species—exclusive heterosexuality is also certainly less than ubiquitous. Animals, like people, have complex life histories that involve a wide spectrum of sexual orientations, with many different degrees of participation in both same- and opposite-sex activities. To the question “Do animals engage in bisexuality or exclusive homosexuality?” we must therefore answer “both and neither.” There is no such thing as a single type of “bisexuality” nor a uniform pattern of “exclusive homosexuality.” Multiple shades of sexual orientation are found throughout the animal world—sometimes coexisting in the same species or even the same individual—forming part of a much larger spectrum of sexual variance.

Nonchalant Onlookers and Gay Ghettos: Social and Spatial Responses