Biological Exuberance: Animal Homosexuality and Natural Diversity

In Red Deer, for example, one study revealed almost all possible combinations. Some Red Deer females who do not participate at all in homosexual activity play the “male” role in reverse heterosexual mounts, while others who are not involved in heterosexual activity play the “female” role in homosexual interactions (or assume both “roles” equally). One female who exhibited the most heterosexual behavior was only the “mounter” during homosexual interactions (i.e., she did not play the “female” role in that context), while the female who showed the most activity in the “male” role during homosexual interactions only played the “female” role in heterosexual interactions.¹⁶ Moreover, as neuroscientist William Byne has pointed out, a “pseudoheterosexual” interpretation taken to its logical conclusion would have to regard each of the animals performing a reverse heterosexual mount as “homosexual,” since each is exhibiting the mounting behavior of the opposite sex (male being mounted, female doing the mounting). We are left with the nonsensical result that same-sex mounting is a “heterosexual” act for some of its participants (those in the “gender-typical” role) while opposite-sex mounting can sometimes be a “homosexual” act for its participants (those in the “gender-atypical” role).¹⁷

Gendering and Transgendering

Just as most examples of homosexuality cannot be attributed to opposite-sex mimicry or “pseudoheterosexual” behavior, many examples of genuine transgender or sexual mimicry are not associated with homosexuality. In species such as northern jacanas, arctic terns, squid, and numerous reptiles and insects, animals imitate the behavior of members of the opposite sex in various contexts without inducing homosexual activity in animals of the same sex. In fact, more often than not such opposite-sex mimicry or behavioral transvestism is associated with heterosexual courtship, mating, or interaction. In jacanas, for example, males regularly adopt the female’s copulation posture to solicit sexual behavior from females, yet this does not trigger homosexual mounting from other males; likewise for male arctic terns that utilize females’ food-begging gestures.¹⁸

Not only is this true for species such as these where homosexuality has not been reported at all, homosexuality and “pseudoheterosexual” behavior (or transgender) often co-occur in the same species without having anything to do with each other. For example, when confronted aggressively by another male, Chaffinch males sometimes adopt the female’s sexual solicitation posture to prevent an attack, yet this does not trigger homosexual mounting by the other male. Nonbreeding males in this species also sometimes behave like females when trespassing on another male’s territory, but this does not cause the other male to begin courting him. Sexual chases between males, as well as female pairing, do occur in Chaffinches, but in contexts that are unrelated to such opposite-sex mimicry. Rufous-naped Tamarin males perform a “pseudo-female” behavior called upward tail-curling, typically used by females as a prelude to mating; however, males use this display during ambivalent or hostile encounters with females and not during episodes of homosexual mounting with other males. Likewise, Mountain Zebra bachelor stallions imitate the facial expressions and calls of mares in heat when they meet territorial breeding stallions, yet this opposite-sex mimicry does not incite homosexual mounting on the part of the territorial stallion. Rather, same-sex mounting in this species takes place almost exclusively between territorial stallions or between bachelors, rarely if ever between a territorial stallion and a bachelor.

Female Black-crowned Night Herons and Kittiwakes, and male Koalas, occasionally perform courtship behaviors typical of the opposite sex, but in none of these cases are such behaviors associated with the homosexual activity that does occur in these species—in fact, they are typical of animals in heterosexual interactions. ¹⁹ In Northern Elephant Seals, too, younger males imitate females specifically to gain access to heterosexual mating opportunities, “camouflaging” themselves from older males (who would attack them if they were discovered trespassing among females). Yet this does not specifically trigger homosexual mounting from the older male, and same-sex mounting is typical of contexts outside of female mimicry in this species. In fact, transgendered individuals in Northern Elephant Seals and a number of other species (e.g., Red Deer, Black-headed Gulls, Common Garter Snakes) are often more successful at heterosexual mating than many nontransgendered individuals—in other words, animals that look and/or act like the opposite sex can actually be “more heterosexual” than ones that do not.²⁰