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{122} Chapter 4
Explaining (Away) Animal Homosexuality

In August 1995 a historic event took place: a special symposium on sexual orientation in animals was held at the 24^th International Ethological Conference (ethologists are zoologists who study animal behavior). This was an unprecedented occurrence: the first time that animal homosexuality was formally recognized by a zoological organization as a legitimate subject of inquiry unto itself. As hundreds of zoologists and other scientists gathered from more than 40 countries around the world to discuss the latest findings and hypotheses, this conference held the promise of inaugurating a new era in the study of animal homosexuality — one characterized by an absence of the judgmental attitudes chronicled in the previous chapter.

Unfortunately, what actually transpired at the conference is symbolic of the pitfalls that have plagued discussions of animal homosexuality throughout the scientific study of this topic. The symposium's stated mission was to explore "behavioral correlates of sexual plasticity"; its organizer's opening remarks even invoked Paul L.Vasey's recent work on primate homosexuality — to the visual accompaniment of giant photographs of human gay couples projected on the screen.¹ Yet only a handful of papers at the symposium even mentioned homosexuality, let alone dealt with it in any depth. Most were concerned with the hormonal and neurological correlates of male and female differences in behavior and anatomy — reflecting the still widespread view that homosexuality is simply an example of gender "inversion" or "gender-atypical" behavior (e.g., males exhibiting "female" behavior patterns and vice versa). Ironically, among the conference attendees were a veritable who's who of zoologists who have observed homosexual behavior firsthand in wild animals — a treasure trove of information on the topic that went virtually untapped by the symposium's organizers and all but unnoticed by the conference-goers.² On the {123} final day of the conference, after it became apparent that animal homosexuality would receive no more than a cursory discussion in any of the formal presentations, one zoologist tacked a hand-scrawled note on the public message-board: "I am looking for examples of homosexual affairs in insects, please contact ..." — a cogent reminder of both the desire for, and lack of, information on this subject at the very locus where it should be most available.

What happened at this conference is not unusual. The scientific discourse surrounding animal homosexuality has been preoccupied with finding an explanation for the phenomenon, often at the expense of providing comprehensive descriptive information about, or acknowledgment of, the actual extent and diversity of same-sex activity throughout the animal kingdom. Rather than being seen as part of a spectrum of natural variation in sexual and gender expression, homosexuality and transgender are viewed as exceptions or anomalies that somehow stand outside the natural order and must therefore be "explained" or "rationalized." In most respects, by trying to answer the question "Why do some animals engage in homosexual behavior?" scientists have simply found an opportunity to continue many of the same homophobic attitudes documented in the preceding chapter (while ignoring the biases inherent in such a question in the first place). Significant numbers of zoologists are willing to concede that same-sex courtship, copulation, and pair-bonding are indeed "sexual" or "homosexual" activities. However, they commonly propose alternative explanations for these behaviors premised on the notion that this activity is still in some way "anomalous" or "aberrant." Ultimately, most such attempts to find an "explanation" have failed outright or are fundamentally misguided. In this chapter we'll explore four such "explanations" that crop up repeatedly in the scientific and popular discourse surrounding animal homosexuality — the idea that homosexuality is an imitation of heterosexuality, a "substitute" activity when the opposite sex is unavailable, a "mistake," or a pathological condition. These explanations need to be addressed not only because they are widespread within the scientific establishment, but also because they form part of the popular mythology surrounding animal homosexuality. Each of these ideas or analyses is in fact incorrect — or at the very least, only partially relevant.

Significantly, each of these explanations has also been proposed at various times as the "cause" or "reason" for human homosexuality, and equally as often shown to be false. In fact, the language and logic of many of these explanations for animals are directly out of the psychopathological analyses of human homosexuality from the 1940s and 1950s (which, in turn, are a continuation and elaboration of earlier prejudicial attitudes about "abnormal" behaviors). So similar are they to the luridly homophobic accounts of these eras that many such descriptions would be entirely interchangeable were it not for use of the word animals in one and people in the other. The nearly seamless continuity between attitudes toward human and animal homosexuality is exemplified by the following pair of "observations," each of which reduces homosexuality to a form of role-playing imitative of heterosexuality:

      «... one woman lying on top of another and simulating in movements the act of intercourse ... gratifies her masculine component ... . Some authorities {124} regard [the partners of these] women ... as pseudohomosexuals. The number of sex-starved women who yield to homosexuality ... is much greater than one might suppose.»
      — F. S. CAPRIO, female homosexuality, 1954

      «female [s] ... occasionally carry out elaborate homosexual pseudocopulatory manoeuvres. Usually one female assumes the male role and mounts another female ... and the two animals then perform a remarkably realistic pseudocopulation.»
     — from a scientific description of Northern Fur Seals, 1959³

Sadly, such perspectives on animal homosexuality are still prevalent today among both scientists and nonscientists alike. In many cases, people are still reapplying to animals the same outmoded views of homosexuality that were used to condemn and pathologize the behavior in humans throughout most of this century. Such "explanations" have since been shown to be untenable (if not downright laughable) for people, and they should similarly have been abandoned long ago by scientists studying animals.

"Which One Plays the Female Role?" — Homosexuality as Pseudoheterosexuality

One of the most prevalent and pernicious misconceptions about animal homosexuality is that it is simply an imitation of heterosexuality and heterosexual gender roles.⁴ In numerous species, animals that participate in homosexual interactions are assigned — sometimes arbitrarily — to one of two roles: "male" or "female." Masculine or feminine, malelike or femalelike, male-acting or female-acting, male mimicry or female mimicry, pseudo-male or pseudo-female are just some of the other terms widely used to refer to the participants in homosexual interactions.⁵ In other words, homosexuality is seen merely as a replica of heterosexuality — male — female patterns transposed onto same-sex partners. In perhaps the most extreme example of this viewpoint, one scientist actually treated the homosexual couples in his captive population of Orange-fronted and Aztec Parakeets as stand-ins for heterosexual pairs. Because of the rather embarrassing fact that there were more same-sex than opposite-sex pairs in his flock, he used several homosexual couples as male-female surrogates in his experiments on "heterosexual" pair-bonding behavior. For this to work, however, "it was necessary ... to assume that in homosexual pairs one bird assumes the role of the male, the other of the female, and that behavioral events between such birds are those typical of heterosexually paired birds." This assumption entirely disregarded the fact that female pairs in this species differ in important respects from heterosexual pairs (for example by exhibiting mutual, as opposed to one-way, courtship feeding) and probably also hindered the discovery of other such differences.⁶
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The idea that homosexual relations in animals are necessarily gendered along heterosexual lines has its origins in Freud's (and others') view of (human) homosexuality as sexual inversion, the adoption by one partner in a same-sex interaction of the behaviors or roles "typical" of the opposite sex.⁷ In fact, some zoologists have used the very terms sexual inversion and inverse (or even reverse) sexuality to describe homosexual activity in animals. Desmond Morris developed this idea further with respect to animals in a series of papers in the 1950s, in which he introduced the terms pseudo-male and pseudo-female to describe animals who exhibit behavior patterns more commonly seen in the opposite sex; these terms are still used to this day in scientific publications that describe same-sex activity.⁸ Also still employed is the analytical framework represented by such terms, which argues that the occurrence of homosexuality in a species can be directly attributed to, and characterized by, opposite-sex or "gender-atypical" behavior. The argument goes something like this: certain animals in a population are prone to "pseudo-female" or "pseudo-male" behavior; that is, imitation of behavioral patterns found in the opposite sex. This mimicking of heterosexuality automatically triggers "homosexual" behavior in individuals who are essentially "deceived" into thinking they are dealing with a member of the opposite sex, hence they respond with sexual or courtship behaviors.

Often, an attempt is also made to correlate sexual "role inversion" with other behavioral or physical traits that are supposedly characteristic of the opposite sex (or of certain gender roles), such as higher levels of aggression in female Takhi and Mallard Ducks that mount other females. One scientist, in describing a male Snow Goose that supposedly adopted the "male role" in a homosexual pairing, even goes so far as to comment on the bird's "much enlarged penis" in addition to his greater aggressiveness. As we shall see later in this chapter, this is reminiscent of descriptions of human "inversion" from the early sexological literature, which often focused on the appearance of a person's genitals as somehow indicative of the "abnormality" or pathology of their homosexuality.⁹

Reciprocal Homosexuality and Heterosexual "Inverts"
      In spite of apparently unabated popularity in scientific circles, a "pseudoheterosexuality" interpretation imposes a restrictive and often erroneous framework on animal homosexuality, and there are numerous arguments against it.¹⁰ To begin with, in an overwhelming number of cases homosexual behavior cannot possibly be construed as mimicking heterosexuality. In a number of species, unique sexual or courtship behaviors occur between animals of the same sex that are not found in heterosexual interactions. For example, homosexual but not heterosexual interactions in Bonobos, Gibbons, Stumptail Macaques, Crested Black Macaques, West Indian Manatees, and Gray Whales often involve mutual genital rubbing or manual and oral stimulation of the genitals.¹¹ The actions of both partners are often identical or reciprocal, and therefore neither animal can be construed as adopting a stereotypically "male" or "female" role.¹² In species such as Bottlenose {126} Dolphins, Cheetahs, and Grizzly Bears (among others), same-sex pair-bonding occurs to the exclusion of opposite-sex pairing; thus, the "roles" of individuals in homosexual pairs cannot be modeled after male-female (heterosexual) "roles" because there simply are no such models in these species.

Even for animals where identical or similar behaviors occur in both homosexual and heterosexual interactions, the same-sex activities often do not fall neatly into the gendered patterns expected under a "pseudoheterosexual" interpretation. For example, homosexual mounting is often reciprocal, which means that the animals take turns in the mounter/mountee positions, with neither preferring exclusively "male" or "female" roles. Various forms of reciprocal mounting have been documented in at least 30 species (and probably occur in many more): simultaneous reciprocity, in which the partners exchange roles during the same mounting bout (as in Pukeko or Black-rumped Flamebacks); and sequential reciprocity, in which partners trade roles at different points in time — the latter can involve frequent alternation over an extended period as in Japanese Macaques, or perhaps a onetime switch as has been reported for some Bottlenose Dolphins. Moreover, in many species heterosexual mounting can be "reversed" or "inverted," in that the female mounts her male partner. Thus, the "mounter" and "mountee" positions cannot be absolutely equated with fixed "male" and "female" roles even in opposite-sex interactions. Most "pseudoheterosexual" interpretations of homosexuality, therefore, involve stereotyped views not only of same-sex activity but also of male-female relations.¹³

Reciprocal, mutual, or non-"inverted" homosexual activities also characterize many other behavior categories besides mounting and sexual activity. In Laughing Gulls and Antbirds, for example, courtship feeding occurs in both heterosexual and homosexual contexts; between two males, however, this activity has a number of distinctive features owing to the fact that neither male is playing a "female" role. Males often engage in reciprocal courtship feeding by passing the food gift back and forth between them, and either partner may initiate the exchange (in heterosexual courtship feeding, typically the male initiates the activity and the female does not reciprocate). In a number of other bird species, including Greylag Geese, Mallard Ducks, Greenshanks, and Humboldt Penguins, both males in homosexual pairs exhibit typically male sexual, courtship, and pair-bonding behaviors, i.e., neither {127} partner adopts a "feminine" role.¹⁴ Likewise, both females in homosexual pairs of Snow Geese, Mute Swans, Lovebirds, Red-backed Shrikes, and Blue Tits incubate eggs — an activity typical only for females in heterosexual pairs of these species — while both males in Emu and Greater Rhea same-sex associations incubate the eggs and raise the chicks (an activity performed only by males in heterosexual associations).

In "pseudoheterosexual" explanations of homosexuality, it is usually assumed that a same-sex interaction is initiated by the animal who is adopting behavior patterns of the opposite sex. That is, a sexual or courtship episode between males is triggered by one male performing typically female "invitations" to the other male, while an analogous interaction between females is initiated by one female making typically "male" advances toward the other. While the initiation of homosexual activities sometimes does follow this pattern, exactly the opposite is seen in as many — if not more — cases. Sexual activity between females is often initiated by the mountee making typically female solicitations or overtures toward another female — this is true for species as diverse as Lions, Squirrel Monkeys, Rhesus Macaques, Hanuman Langurs, and Sage Grouse. Conversely, it is also common for sexual interactions between males to be initiated by the mounter making a typically "male" approach to another male. Even in courtship activities, the "roles" of the participating animals often do not fall into the patterns predicted by a "pseudoheterosexual" interpretation. In Ostriches, for example, homosexual courtships are not prompted by "female" behavior on the part of a male, but rather are initiated by one male approaching another using behaviors unique to same-sex interactions. Similarly, male Musk Ducks perform their courtship displays without being "triggered" by female behaviors on the part of either males or females; rather, Ducks of both sexes are attracted to males who are already displaying.

Often only one animal in a same-sex interaction is classified by scientists as truly "homosexual" — the one engaging in the putative "gender-atypical" behaviors. Thus, a male animal that solicits and is mounted by another male is considered to be the "true" homosexual, while the male who mounts him is a "normal" heterosexual male who is reacting to "opposite-sex" mimicry. This kind of logic frequently leads to absurd and contradictory classifications of animals. We've already discussed cases of reciprocal mounting, where the exchange of "roles" between animals necessitates a corresponding switch in which one is considered to be engaging {128} in "homosexual" behavior for the moment. Sometimes an animal is actually both mounter and mountee simultaneously: in Wolves, Laughing Gulls, Little Blue Herons, Sage Grouse, and other species, an animal mounting another individual (of the same or opposite sex) is sometimes itself mounted by an animal of the same sex. Thus, an individual can exhibit gender "typical" and "atypical" mounting behavior at the same time and can perform concurrent "homosexual" and "heterosexual" acts with same-sex partners. In other cases, these behaviors occur in the same individual but separated in time, and in ways that do not conform to a "pseudoheterosexual" interpretation. Typically, the "true" homosexual animal is thought to be limited to opposite-sex behavior patterns and hence incapable of actual heterosexual relations (e.g., a male playing the "female role" with a male partner is considered incapable of playing the "male role" with a female partner). However, bisexual animals who successfully mate and breed with opposite-sex partners often perform the "gender-atypical" role during their homosexual interactions, while strictly heterosexual animals may perform the "gender-atypical" role during their heterosexual interactions — showing that there is no necessary connection between homosexual and heterosexual "roles."¹⁵

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 {129} 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

In a number of animals, some homosexual interactions have characteristics that could be interpreted as involving "pseudoheterosexuality" or transgendered behaviors, yet these constitute only a portion of same-sex activity in the species — and hence, only a partial "explanation," at best, for the occurrence of these activities. In Tasmanian Native Hens, for example, males adopt a posture following heterosexual copulation that resembles the female's invitation to mate — yet only one homosexual mounting recorded in this species was apparently triggered by this posture; the rest occurred in other contexts. Rhesus Macaque females who mount other females sometimes display typically "male" behaviors such as various {130} head movements, the way they carry their tails, or other patterns — but just as many females, if not more, do not exhibit these behaviors as a part of their homosexual interactions.²¹

Perhaps the most compelling example of how homosexuality, transgender, and gender roles interact in unexpected ways concerns "femalelike" males in Mountain Sheep. In Bighorn and Thinhorn Sheep, being mounted by another male is a typically "male" activity. As described in chapter 1, most males participate in homosexual mounting throughout the year, while females generally refuse to allow males to mount them except for the two or so days out of the year when each of them is in heat. Consequently, transgendered males — rams who associate with females throughout the year (unlike most other males) and exhibit other female behavioral characteristics — do not typically allow other males to mount them. In other words, homosexual activity is characteristic of "masculine" males rather than "feminine" males in these species. Moreover, because same-sex mounting has such primacy in the social organization of these animals, heterosexual activity is actually patterned after homosexual interactions and not the other way around. Females in heat typically imitate the courtship patterns of male homosexual interactions in order to arouse the sexual interest of males — a remarkable example of the exact opposite of a "pseudoheterosexual" pattern.²²

Homosexual "Role-Playing": Gender Blending and Amalgamation
      In many animals gender roles of some sort do exist in homosexual interactions, but it is overly simplistic to consider these mere replicas of male and female behaviors. Gendered activities in a same-sex context are never an exact copy of heterosexual roles, and in many cases animals actually exhibit a complex mixture of male and female behavior patterns. This type of gender-role mixing assumes three basic forms: a continuum among individuals, role-differentiated combinations, and behavioral amalgams.²³ In some species, individuals vary along a scale or continuum in the extent to which their behaviors in homosexual interactions resemble "male" or "female" patterns. In Kob antelope, for example, some females utilize the full array of courtship patterns typically employed by males, others make use of none or few of these, while most females range somewhere in between these extremes.²⁴ Ruff males fall into four categories along a spectrum of most "malelike" to most "femalelike" in terms of appearance (presence and color of neck ruff, size), aggressive behavior, courtship behaviors, and other characteristics. However, these categories cut across aspects of sexual behavior, including participation in the "male" role of mounter and the "female" role of mountee in homosexual interactions. The most "malelike" males (residents) perform both roles as do the most "femalelike" males (naked-napes), while of the intermediate categories, some participate in both roles (satellite males) and some rarely engage in either (marginal males). In a number of species such as Gorillas, Hanuman Langurs, and Rhesus, Bonnet, and Pig-tailed Macaques, some individuals clearly prefer (or end up mostly participating) in the "mounter" as opposed to the "mountee" roles during same-sex activity, while for other individuals the reverse is true. Yet these patterns represent the two poles of a {131} continuum, since many individuals in these species actually fall along the entire range in terms of their mounting activities.²⁵

To specifically address the question of "pseudoheterosexual" roles, scientists studying homosexual pairing in Western Gulls made detailed observations regarding whether one partner is more "feminine" and the other more "masculine," in terms of which courtship, sexual, and territorial behaviors they exhibit. They found that most females employ a mixture of typically male and typically female patterns, although pair-bonds vary in the extent to which there is role differentiation between the partners. In some pairs, one bird performs the majority of mounting and courtship feeding (typically "male" activities) and less "head-tossing" (a typically "female" courtship behavior). In others, there is less of a distinction between the two partners, while in still others the two females participate nearly equally in gendered behaviors. Overall, however, scientists found that both partners in homosexual pairs are more similar to heterosexual females than to males in terms of the amount of time they spend on their nesting territories and their aggressive responses to intruders.²⁶

Another pattern of gender mixing involves role-differentiated combinations, in which same-sex interactions are largely gendered or separated into "male" and "female" roles, yet each individual still combines elements of both to varying degrees. This is a crossing or intermixing of "masculine" and "feminine" traits — in the domains of sexual, courtship, or parenting and pair-bonding behaviors — set against an overall pattern of polarity between the two. For example, male couples in Hooded Warblers often divide up their parenting duties into typically male and female roles: one male builds the nest and incubates the eggs ("female" duties) while the other defends the territory and sings ("male" activities). Yet layered on top of this are more subtle meldings of gender roles: the more "feminine" partner may also engage in the typically male activity of singing (although with a distinctive song type), while the more "masculine" partner may also feed his mate during incubation (an activity rarely exhibited by either partner in heterosexual pairs).²⁷

Other examples related to pair-bonding and parenting activities abound. The "masculine" partner in some Canada Goose (and Chiloe Wigeon) lesbian couples still carries out the quintessentially female activities of egg laying, incubation, and nest-building (the latter usually done only by females in these species). One female in Orange-fronted Parakeet homosexual pairs typically performs the "male" activity of nest-tunnel excavation, yet both partners may initiate courtship feeding (characteristic of males in opposite-sex pairs). And in Mute Swan female pairs, one partner stands guard and defends the territory (like a male), yet both females lay eggs (and both build the nest, typical also of both partners in heterosexual pairs). Some Lovebirds in same-sex pairs are role-differentiated, while others engage in combinations of "male" and "female" courtship and sexual activities. In either case, though, if two females are involved, they both perform the typically "female" roles of nest-building, egg laying, and incubation, while neither of two paired males shows any interest in nest-building (which is not characteristic of either heterosexual role). Some "feminine" partners in Chaffinch lesbian couples also exhibit characteristically male behavioral patterns such as singing, while both partners in {132} role-differentiated Jackdaw homosexual couples (or trios) preen each other — a behavior typical only of females in heterosexual pairs. Similar patterns are to be found where sexual and courtship activities are concerned as well. In Long-eared Hedgehog lesbian interactions, for example, one female may be more "malelike" in initiating and carrying out various courtship and sexual behaviors, yet both partners may perform characteristically "female" invitation postures or typically "male" mounting attempts. Likewise, in courtship interactions between male Victoria's Riflebirds or Blue-backed Manakins, the more "femalelike" partner that is being courted often responds with his own distinctly male display patterns.²⁸

A final type of gender-role mixing seen in homosexual interactions involves behavioral amalgams — more balanced combinations of "male" and "female" traits in the same individual, a sort of behavioral "androgyny." This can involve sexual activities: during homosexual interactions between male Gorillas, for instance, the mounter (i.e., the animal "playing the male role") usually also "plays the female role" of initiating the interaction (female Gorillas typically initiate sexual activity in heterosexual contexts). Mallard females who perform the "male" activity of mounting other females nevertheless display postcopulatory behaviors typical of females, while the mountee in male Black-crowned Night Heron homosexual encounters may perform typically "male" courtship behaviors. The mounter in Hanuman Langur female homosexual encounters often exhibits otherwise "female" behaviors such as initiating the sexual interaction and grooming her partner following the mount. Behavioral amalgams can also involve courtship and parenting activities. When one male Emu is courting another, for example, he stretches his neck and erects his neck feathers — a behavior characteristic of both females and males in heterosexual courtships²⁹ — yet neither male makes the booming vocalization typical of females, and each may follow the other (usually only males follow females in heterosexual courtships). Younger male Swallow-tailed Manakins that are courted by adult males exhibit a combination of male and female behavioral traits that makes them distinct from either (and also parallels their plumage, which is a mixture of adult male and female appearance). Their vocalizations and participation in some noncourtship displays are distinctly masculine, while their generally quiet and inconspicuous demeanor is unlike adult males, and in courtship interactions they may assume the role that the female usually does.³⁰ In Snow Goose homosexual pairs, both females perform typically female activities such as incubation and typically male activities such as defense of the goslings.³¹

A multiplicity of gender-role mixtures that defy categorization into any of these three types is the norm in species like the Black-headed Gull. Detailed comparisons of both heterosexual and homosexual pairs showed that birds in same-sex pairs exhibit neither stereotypically "male" nor "female" behaviors. Rather, the frequency with which they perform various courtship and pair-bonding activities tends to be distinct from, or intermediate between, that of both males and females in opposite-sex pairs. For example, the maximum rate of "ceremonial encounters" (a type of courtship interaction) in homosexual pairs exceeds that of both partners in heterosexual pairs. On the other hand, rates of "long-calling" and "head-flagging" (other {133} forms of courtship) tend to be intermediate between those of heterosexual males and females, while the rate of courtship "begging" by males in homosexual couples is generally as low as that of males in heterosexual pairs (which itself is generally lower than that of heterosexual females).³² In addition, both males in homosexual pairs usually build the nest (which is a typically "male" activity in heterosexual couples), although there is also variation between individuals in this regard, with only one partner contributing to the nest in some male pairs.

The "pseudoheterosexual" interpretation of animal behavior offers striking parallels to stereotypical views about human homosexuality. Scientific puzzlement over assigning animals "male" or "female" roles echoes the refrain often heard by gay and lesbian people, who are frequently asked, "Which one plays the man (or woman)?" The assumption is that homosexual relationships must be modeled after heterosexual ones — a view that is as narrow a conception of human relationships as it is of animal sexuality. Each partner in a gay or lesbian relationship (or sexual encounter) is thought to "play" one-half of a heterosexual couple. In reality, far more complex and multidimensional expressions of gender categories are involved, even (or perhaps especially) when the partners appear most "heterosexual" to outside observers. Some people do not structure their homosexual interactions along gendered lines at all; others do, but re-create typically "male" and "female" patterns in new configurations. To give just one example: butch-femme lesbian relationships have long been viewed as simplistic imitations of heterosexuality, in which the butch partner is the "man" and the femme partner is the "woman." Lesbians whose erotic lives are organized along these lines, however, describe eloquently how their actual experiences are far different from this. Neither partner is "copying" heterosexual roles; rather, each is taking elements of masculinity and femininity and alloying them in different combinations and intensities to create female-specific genders. As one lesbian has said about the kind of women she is attracted to, a masculine lesbian is not an imitation man, but a real butch.³³ If even this most superficially "heterosexual" gender presentation is more than what it appears, imagine the possibilities when homosexual interactions are gender-role-defined in other ways, or not at all. Such "possibilities" are in fact everyday realities in the lives of both humans and animals.

Over the past thirty years, a sophisticated analysis of gender categories has been emerging from within the feminist, gay and lesbian, and transgender movements, one that challenges basic notions such as "male" and "female," "masculine" and "feminine," "mannish" and "effeminate." These movements are also calling for a recombining and reimagining of categories such as these, rather than simply their denigration or abolishment. Unfortunately, zoologists for the most part are still operating under an earlier, outmoded conception of gender roles (both heterosexual and homosexual) — one that is inconsistent with the actualities of sexual and gender expression within the animal and human worlds. If any progress is to be made in the study and understanding of animal homosexuality and transgender, scientists and nonscientists alike will need to acquire the sort of multifaceted view of gender and sexuality that is now being articulated within these human liberation movements.
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"The Lengths to Which Deprived Creatures Will Go" — Homosexuality as Substitute Heterosexuality

One of the most prevalent myths about animal homosexuality is that it is invariably caused by a shortage of members of the opposite sex. This is typically attributed to skewed sex ratios in the population (more males than females, or vice versa), or the unavailability of opposite-sex partners due to sex segregation, hostility or indifference on the part of potential mates, or other factors. This belief is widespread among nonscientists and is also the most common "explanation" that biologists have proposed for the occurrence of homosexual behavior in animals. In more than 65 species of mammals and birds, for example, same-sex activity is claimed by zoologists to result from individuals being "unable" to mate heterosexually. Sometimes this is attributed to a predominance of one sex over the other in wild or captive populations: the formation of lesbian pairs in Australian Shelducks and Ring-billed Gulls, for instance, is supposedly "caused" by an excess number of females (65 percent females in Shelduck populations, 55 percent females in Ring-billed Gulls).

Homosexual pairs in Mute Swans occurring in populations with unbalanced sex ratios are said to be "examples of the lengths to which deprived creatures will go to satisfy their natural urge to reproduce." In some cases, homosexual behavior is labeled a "substitute" for heterosexuality or "redirected" heterosexual behavior, resulting from a variety of factors. For example, it is claimed that individuals are "prevented" from mating with (or otherwise having access to) the opposite sex by other (often higher-ranking) animals, or by the overall social organization (e.g., in Mountain Sheep, Bottlenose Dolphins, or Killer Whales). Alternatively, it has been suggested that individuals resort to homosexuality when their heterosexual advances are met with refusal or disinterest (e.g., in White-handed Gibbons, West Indian Manatees, Asiatic Elephants). In a few cases (e.g., Hanuman Langurs, Lions, Sage Grouse) scientists have even suggested that females turn to one another because they have not been "satisfied" or received enough attention from male partners — a version of the widespread stereotype about the "cause" of lesbianism among people.³⁴

The line of reasoning in "explanations" such as these is curious, since it implies that unless there is an adequate supply of the opposite sex, homosexuality will inevitably ensue. This is actually an unintentional assertion of the relative strength of the homosexual urge, or correspondingly, the relative weakness of the heterosexual imperative — for the stronghold of heterosexuality must be tenuous indeed if such factors are capable of upsetting the balance. Besides this, however, unavailability of the opposite sex — what we will call the shortage hypothesis — is simply incompatible with the facts.

Surplus Homosexuality
      The shortage hypothesis cannot be a universal explanation for animal homosexuality because of the many examples of animals engaging in same-sex activity {135} when opposite-sex partners are freely available.³⁵ In Orang-utans, Japanese Macaques, Stumptail Macaques, Rhesus Macaques, Common Gulls, Black-headed Gulls, King Penguins, Galahs, and more than 40 other species, scientists have documented individuals either ignoring opposite-sex partners and seeking out same-sex partners instead, or else engaging in homosexual activity more or less concurrently with heterosexual activity (i.e., even when opposite-sex partners are accessible, as already mentioned in the discussion of simultaneous bisexuality).³⁶ In fact, in a surprisingly large number of species, homosexual activity is positively correlated with heterosexual activity: same-sex interactions actually increase as animals gain access to opposite-sex partners and decrease in their absence. This is the exact reverse of what would be expected if homosexuality resulted from a lack of access to heterosexual mating opportunities.

Homosexual activity among male Bottlenose Dolphins in captivity, for instance, actually declined when females were removed from their tank, while aggressive interactions between the males increased. Conversely, female Squirrel Monkeys in one study engaged in virtually no homosexual activity when kept in same-sex groups, yet showed significant rates of homosexual mounting and other activities (along with heterosexual behaviors) when males were introduced into their group. Another study of this species found that females with the most attention from heterosexual partners also engaged in the most homosexual pursuits. In Bonobos, Stumptail Macaques, Savanna (Yellow) Baboons, and West Indian Manatees, same-sex activity is often stimulated by opposite-sex activity (and vice versa), with the result that sessions may involve both heterosexual and homosexual encounters among multiple participants. Homosexual mounting in Pukeko is most prevalent in breeding groups that have the greatest amount of heterosexual activity, while homosexual mounts in Common Murres become more common as promiscuous heterosexual mounts also increase in frequency (although the latter may, ironically, result from a decrease in available females). In some species, individuals that participate in the most heterosexual matings may also engage in the most homosexual ones, as in Sociable Weavers and Bonnet Macaques. Conversely, animals that are the least active heterosexually are often the least active homosexually. In Ruffs, for example, the class of males who do not generally mate with females (known as marginal males) also rarely participate in homosexual matings, while in one study of Japanese Macaques, the only female who did not consort with any other females also failed to consort with any males.³⁷ Finally, in a number of species such as Swallows, Laysan Albatrosses, and Herons, same-sex mounting occurs primarily among breeding individuals (i.e., those who already have heterosexual mates) and is largely absent among nonbreeders.

A number of species do have skewed sex ratios, but (like dominance) this is neither a sufficient nor a necessary prerequisite for the occurrence of homosexuality in a population. Male homosexuality is not reported for red-winged blackbirds or giant cowbirds, for example, even though some populations are 80-84 percent male, nor for pintail duck populations with two-thirds males, or kiwis with 58 percent males, or purple finches with 57 percent males. Likewise, female homosexuality is absent in boat-tailed grackles even though males may comprise only a third of the {136} population, and in sparrow hawks, where there is also a "surplus" of females (less than 40 percent males). In contrast, homosexuality occurs in numerous species or populations that have equal (or nearly equal) sex ratios, including Bonobos, Bonnet Macaques, West Indian Manatees, Snow Geese, California Gulls, and Pukeko.³⁸ Moreover, closely related species or different populations of the same species that have identical (or similar) sex ratios and forms of social organization often exhibit strikingly different patterns of homosexuality. Many Seals and Sea Lions with polygamous mating systems, for instance, have strongly female-biased sex ratios (three to five females for every male) and social systems that often include sex segregation and/or exclusion of large numbers of males from breeding opportunities. Some of these species exhibit male homosexuality (e.g., Gray Seals, Northern Elephant Seals, Walruses), others have female homosexuality (e.g., Northern Fur Seals), some have both (e.g., Australian Sea Lions), while the majority have no homosexuality at all (e.g., California sea lions, southern fur seals). Likewise, lunulated antbirds, salvin's antbirds, Bicolored Antbirds, and Ocellated Antbirds all live in populations that have an excess of males, yet homosexual pairing is only found in the latter two species.³⁹

In many animals that have skewed sex ratios, homosexuality only occurs (or is more common) in the sex that is in shorter supply rather than in the "surplus" sex. In some populations of Crab-eating Macaques, for example, females outnumber males by more than two to one, yet same-sex activity only occurs among males. Female homosexuality accounts for more than 80 percent of same-sex activity in Pukeko even though some populations are more than 70 percent male. The reverse is true for Rhesus Macaques: in some populations females outnumber males nearly three to one, yet the majority of same-sex activity (over 80 percent) is between males. Tree Swallow populations often have a surplus of females, but only male homosexuality occurs. Likewise, female pairs have formed in captive populations of Galahs and Scarlet Ibises that have an excess of males, while male pairs of Flamingos are reported from populations that have more females than males. In Nilgiri Langurs, there is a female-biased sex ratio in the overall population (and individuals live in groups with more females than males), yet only male same-sex activity is reported. Finally, in Little Egrets and Little Blue Herons there is a "surplus" of unpaired males, yet same-sex mounting occurs almost exclusively among paired males rather than in the population of birds that are unable to find heterosexual mates.⁴⁰

While homosexual activity in some species may appear to be associated with an unavailability of the opposite sex, the patterns of its occurrence are often far more complex than a shortage explanation would indicate. Although lesbian pairs in Black Stilts, for example, generally do occur in populations where the sex ratio is biased toward females, in other populations of the same species with a surplus of males, no male homosexual pairs have formed. The same is true, in reverse, for captive Humboldt Penguins: male pairs form when there is a surplus of males but female pairs do not form when there is a surplus of females. Among some populations of Savanna (Yellow) Baboons, the sex ratio becomes skewed among older juveniles, where males outnumber females two to one — and indeed, 10 percent of such animals' mounting is homosexual. However, the sex ratio is equal among adults and {137} younger juveniles, and the prevalence of homosexual mounting in these segments of the population is the exact opposite of what the shortage hypothesis would predict: 17-24 percent of their mounting is same-sex. In other words, older juvenile males actually exhibit the lowest proportion of homosexual activity and the greatest participation in heterosexual mounting of any segment of the population (accounting for more than half of all male-female mounts), even though their age group contains the greatest surplus of males. Sex ratios in wild Mallard Ducks fluctuate during the breeding season, with fewer females being present in some months than others. Although male pairs sometimes form at these times, during other months when there is also an excess of males in the population, there are no male pairs.⁴¹

If access to heterosexual mates were the only factor involved in the occurrence of homosexuality, both males and females in sex-segregated populations should exhibit the same degree of homosexual activity. However, in the majority of species that have some form of sex segregation, homosexual activity is found in only one sex (e.g., Walruses, Gray Seals, Warthogs, American Bison) or is much more common in one sex (usually males) than the other (e.g., Giraffes, Blackbucks, Mountain Sheep, Australian Sea Lions). Conversely, in some species that have unbalanced sex ratios (in wild or captive contexts), such as Pig-tailed Macaques, Bottlenose Dolphins, Cheetahs, Koalas, Canada Geese, and Flamingos, homosexuality occurs in both sexes (although it may be more common in the "surplus" sex). This indicates that more is involved than simply a "shortage" of available heterosexual partners.⁴² Likewise, where populations of the same species vary in their sex ratios, homosexuality is sometimes less common in nonskewed populations, but it is still present. In Japanese Macaques, Giraffes, and Greylag Geese, for example, same-sex activity may increase in populations with an excess of one sex, but it still occurs at a fairly steady rate in other circumstances regardless of the sex ratio and may even be present in the "limiting" sex (e.g., in Giraffe populations with more than 60 percent females, male homosexuality still occurs). Even in populations of Japanese Macaques with highly skewed sex ratios, most individuals still manage to participate in both heterosexual and homosexual activities, indicating that they are not turning to same-sex partners as a result of being completely "deprived" of opposite-sex partners.⁴³

Similarly, in a number of species where homosexuality sometimes occurs in the absence of opposite-sex partners (due to sex segregation, heterosexual refusal, captive situations, etc.), same-sex activity is not limited to these contexts, but also occurs in mixed-sex groups (e.g., Gorillas, Hanuman Langurs, Crested Black Macaques, Squirrel Monkeys, Walruses, Lions, Mallard Ducks, Black-headed Gulls) or in contexts where it is not a response to the refusal or unavailability of the opposite sex (e.g., West Indian Manatees, Cheetahs).⁴⁴ If same-sex activity were due entirely to an absence of the opposite sex, it should disappear completely once opposite-sex partners are available, yet these examples show that it does not. Conversely, homosexuality does not arise automatically or immediately when animals are deprived of opposite-sex partners, nor does heterosexuality necessarily ensue once they have access to such partners. Homosexual activity in a captive group of female Squirrel Monkeys, for instance, did not develop until fully one year after they had been sequestered away from males, while female Long-eared Hedgehogs {138} that were homosexually involved with each other in the absence of males did not participate in heterosexual mating for more than two years after they were given access to males.⁴⁵

Multiple Possibilities
      Even if homosexuality in some species only occurs in populations where there is more of one sex than the other, this is, at the very least, evidence of a "latent" bisexual capacity among some individuals. Moreover, the skewed sex ratio is probably only a contributing factor rather than a determining "cause" of same-sex interactions in such cases. Typically only a portion of the "surplus" sex in these populations actually participates in homosexuality, and sometimes "available" opposite-sex partners are even passed over. This is most obvious in Silver Gulls, where nearly half of all females are "unable" to find a male partner each year, yet lesbian pairs constitute only about 6 percent of the population — in other words, the vast majority of "surplus" females remain single rather than forming homosexual pairs. Furthermore, about 14 percent of all males are unpaired, which means that females who form same-sex bonds do so in spite of the presence of single males in the population. Likewise, some female Mallard Ducks remain unpaired even in populations with more males than females. In one semi-wild population of Canada Geese with an excess of males, some of the unpaired males failed to form homosexual pairs; furthermore, some females also remained unpaired or formed homosexual bonds even though opposite-sex birds were "available." While approximately 10 percent of widowed Jackdaws form homosexual pair-bonds, the majority of widowed birds who do not find male partners actually remain single rather than pairing with female partners. Lesser Scaup Duck populations generally consist of 60-80 percent males, yet only a fraction of these individuals engage in homosexual mounting (and none form homosexual pair-bonds). Similarly, herds of Caribou may contain only 30-40 percent males, yet same-sex activity among females is not overwhelming.⁴⁶ Other species in which only a portion of the "surplus" individuals form same-sex bonds include Flamingos, Laughing Gulls, Humboldt Penguins, Gentoo Penguins, Pied Kingfishers, Peach-faced Lovebirds, Galahs, and Bicolored Antbirds.⁴⁷

Although homosexual involvements in such species may be the "result" of skewed sex ratios, any "explanation" of homosexuality that relies on this factor alone needs to address why only some individuals "choose" this strategy, and why this strategy rather than another. For in addition to remaining single or forming same-sex pair-bonds, a wide variety of other behavioral responses occur among animals in populations that have a surplus of one sex, or in situations where the opposite sex is "unavailable." For example, in many otherwise monogamous species that have more females than males (or vice versa), some individuals form polygamous heterosexual trios (so-called "bigamy") or even quartets ("trigamy"). These options occur alongside homosexual pairings in Flamingos and Humboldt Penguins, and instead of same-sex pairing in Cattle Egrets, emperor penguins, and dippers (among many others). Individuals in the same population may also adopt {139} different strategies or combine these strategies, to varying degrees: in Oystercatcher communities, for instance, with large surpluses of nonbreeding birds unable to find heterosexual mates or breeding territories of their own, only a small fraction of these birds form polygamous trios (most remain unmated); and only a portion of these in turn go on to develop homosexual bonds within their trio. Australian noisy miners (a bird species with a heavily male-biased sex ratio) have developed a complex, specieswide system of communal breeding that involves, among other arrangements, polyandry (several males associating with each female, without any same-sex bonding). The reverse situation occurs in spotted sandpipers, in which "surplus" birds actually participate in monogamy rather than polygamy. In this species, females usually mate with several males and generally leave the parenting duties to them; females unable to find polygamous mates, however, often "revert" to monogamous (heterosexual) pairing and parenting, helping one male partner with incubation and brooding.⁴⁸

Polygamy is just the tip of the iceberg as far as alternate strategies are concerned. Surplus female Redshanks participate in promiscuous matings with already paired males rather than forming bonds involving other females; "extra" male mustached warblers help already established pairs raise their families; while surplus female Ostriches and Greater Rheas lay their eggs in other females' nests or abandon them rather than forming bonds with either males or females. Female Tree Swallows, male tropical house wrens, and male barn swallows unable to find mates of their own often invade the nests of existing heterosexual pairs and forcibly acquire a partner (either through direct attack and eviction of the other mate, or by killing their young and causing the pair's breakup). In some species of Penguins and Egrets, individuals form temporary or serial heterosexual pair-bonds or divorce their partners more often in response to a surplus of one sex. In Black Stilt populations with a surplus of one sex, birds regularly seek heterosexual partners outside their species (hybridizing with the closely related Black-winged Stilt), while female Silver and Herring Gulls in some colonies with a "shortage" of adult males often simply pair with much younger males. A common response of male African Elephants that are sexually aroused but unable to find receptive female partners is simply to roll in mud wallows or take dust baths (thereby perhaps "diffusing" their arousal), rather than engaging in any sexual behavior (with either males or females). In all of these species, homosexual activity (if it occurs at all) is simply one "option" that some individuals adopt alongside many other alternatives.⁴⁹

A shortage explanation cannot adequately account for the occurrence of such multiple strategies, or for the choice of one over the other. By claiming that animals "resort" to homosexuality in times of need, scientists often overlook other more plausible (heterosexual) alternatives — unintentionally providing support for the idea that homosexuality may actually be the most appealing option for some individuals in these circumstances. For example, homosexual activity in White-handed Gibbons has been attributed to the unavailability (or unwillingness) of a male's female partner to have sex with him. But why don't such males seek heterosexual matings outside of their pair-bond or simply masturbate (strategies that both occur in other contexts for this species)? Likewise, homosexual courtships in Ostriches are {140} claimed — in a particularly convoluted sequence of logic — to result from a balanced sex ratio in some populations. Because Ostriches often mate polygamously — one male with several females — a population that has equal numbers of males and females would supposedly be unable to support such multiple matings. One scientist suggested that in this case males turn to their own sex — but why would this occur instead of males simply remaining in monogamous heterosexual pairings (as do spotted sandpipers)? Some same-sex mountings in Buff-breasted Sandpipers are said to result from the scarcity of females late in the breeding season. But once females stop visiting the breeding territories at this time, males often move their courtship displays to where the females are (at their nests) and may even copulate with them during the egg-laying period. Why would some males "resort" to relocating their heterosexual activities, while others would "abandon" them for homosexual activities?⁵⁰ Even if same-sex activity in these species could be attributed to the unavailability of the opposite sex, important questions such as these remain unaddressed under a shortage explanation. On the other hand, if participation in homosexuality is seen as the expression of individual variability and plasticity in sexual orientation — rather than as being "caused" or "determined" by a shortage of the opposite sex — then the variety of sexual responses and capacities actually seen in such circumstances is no longer incongruous.

Deprived of Heterosexuality?
      One particularly common version of the shortage explanation is that males turn to homosexuality after being prevented from mating with females, due to the active interference or inhibiting presence of higher-ranking males. This is often suggested for mammals with polygamous or promiscuous mating systems in which only relatively few males ever get to mate heterosexually. While this may contribute to same-sex activity in some species (e.g., Mountain Sheep, Northern Elephant Seals), there is considerable evidence that this explanation is overly simplistic. Homosexual mounting in American Bison, for instance, is especially common among younger males that do not breed (ages one to six), but this cannot be attributed solely to their being "denied" access to females by older, higher-ranking males. Same-sex activity is much less common among bulls four to six years old than it is in males one to three years old, even though both groups are "prevented" (or abstain) from engaging in breeding activities. Also, studies of populations in which older bulls have been removed (in order to give younger males more "access" to females) show that although heterosexual activity increases among the younger bulls in the absence of the higher-ranking males, so does homosexual activity. In fact, more than 55 percent of mounts in such groups are still between males even though there are no older bulls to "prevent" the males from mating heterosexually (and even though females outnumbered males in such populations). Likewise, as they are growing up, male Bonobos experience a sharp drop in their access to heterosexual partners that is not reflected in a corresponding increase in their homosexual activity. As infants and juveniles they are very sexually active with mature females, but once they reach adolescence, they are generally prevented by older males from {141} interacting sexually with females. However, their participation in same-sex activity increases steadily throughout this period rather than rising sharply when female partners become "unavailable" (or dropping when they are once again available). In fact, homosexual activity reaches its maximum level during adulthood when heterosexual activity also peaks.⁵¹

Although younger male Musk-oxen may be excluded from heterosexual mating opportunities by older males, this does not "cause" the homosexual activity that occurs in this species. Courtship and mounting activity between males generally takes place in the breeding (harem) herds and is initiated by adult bulls toward yearlings — in other words, by the males who do have access to females. Most other adult males are excluded from breeding as well, yet homosexual behavior is not characteristic of the all-male herds where such bulls often spend much of their time. Additionally, in captive groups lacking older males to "prevent" heterosexual mating, homosexual mounting still occurs at a fairly high rate alongside opposite-sex mounting. Likewise, homosexual behaviors in male Asiatic Elephants occur in both breeding and nonbreeding individuals. When older or higher-ranking males (who usually monopolize female partners) are prevented from mating heterosexually in captive groups, younger or lower-ranking males are then able to copulate with females. However, same-sex activities continue in both age/rank groups regardless of whether they have access to female partners or not. In fact, males who are heterosexually active may exhibit higher levels of homosexual activity than those who do not mate with females. In New Zealand Sea Lions, most younger males are excluded from breeding, but homosexual activity also occurs among adult breeding males. Lower-ranking male Wolves are prevented from mating with the highest-ranking female in the pack, but rather than mating with the available lower-ranking females, such males often mount each other. Finally, although homosexual activity in adolescent Killer Whales is attributed to their exclusion from heterosexual mating opportunities, adult males who have access to females also sometimes participate in same-sex activity. In addition, adolescents spend roughly the same proportion of their time as do adults engaging in sexual and related social behaviors with females.⁵²

Homosexual activity in birds also generally fails to be correlated with patterns of exclusion from (or nonparticipation in) heterosexual mating. In Ruffs, for instance, mountings between males are actually more common when females are present on the breeding grounds than when they are absent. Even though males sometimes do try to prevent each other from mating heterosexually, same-sex mounts are not simply "redirected" or "substitute" heterosexual copulations. Homosexual mounts occur among a variety of different classes of males even when they are not directly "prevented" from mating with females (such as individuals known as satellites and naked-nape males). Conversely, one class of males — so-called marginal males — that is routinely excluded from opposite-sex interactions (by direct attacks from other males) does not usually engage in homosexual activity either. In Pukeko, a significant portion of the population assists other birds in raising their young rather than breeding themselves; however, homosexual activity in this species is characteristic of breeding individuals rather than such nonbreeding "helpers." In Ocher-bellied {142} Flycatcher and Ruffed Grouse populations that have a "surplus" of nonbreeding birds, breeding territories often go unused, indicating that nonbreeders are not being "prevented" from mating heterosexually (or at least are choosing to remain nonbreeders until better territories become available). Moreover, only a portion of such nonbreeders ever participate in same-sex activity, which in these species generally involves at least one partner that does have his own breeding territory. Likewise, the incidence of homosexual bonding among Oystercatchers (in the form of bisexual trios) does not increase significantly under higher population densities, when many individuals are unable to acquire their own opposite-sex mates and breeding territories. Brown-headed Cowbird populations generally have a significant surplus of males, and higher-ranking males also actively prevent lower-ranking males from courting and pairing with females. Yet the large number of birds thereby "excluded" from heterosexual mating opportunities — half to two-thirds of all males — do not regularly court or mate with one another. In fact, the only homosexual activity observed in this species involves male Cowbirds occasionally being mounted by males of another species, House Sparrows. Finally, Guianan Cock-of-the-Rock exhibit a pattern of homosexual and heterosexual participation that is strikingly similar to that of American Bison. Both yearling and two-year-old males are generally "excluded" from breeding, yet extensive homosexual activity only occurs in the former age group — and almost always with adult males as partners, many of whom are not excluded from heterosexual mating.⁵³

Homosexuality is not generally the result of animals being "deprived" of heterosexual mating opportunities — this can be seen quite clearly in the behavior of individuals toward members of the opposite sex in skewed or segregated populations (in both the wild and captivity). Potential heterosexual partners are often ignored or even actively refused in such situations — they are rarely inundated with attentions as would be expected if animals were being excluded from participation in opposite-sex mating. In Giraffe populations with a majority of males, for instance, females are not swamped with heterosexual attentions, and mating opportunities with females are sometimes even bypassed in favor of homosexual mounting and other activities. Female Japanese Macaques and Hanuman Langurs engaging in homosexual activities usually disregard males entirely and may actually threaten or attack them if they make sexual overtures. Gray Seal and Killer Whale homosexual activities usually take place in all-male groups; although a few females are occasionally present in such groups, they are subject to little sexual attention from the males, the majority of whom ignore them altogether. This is in stark contrast to the often violent sexual attacks by large numbers of males on females during the breeding season in Gray (and other) Seals. Female Plains and Mountain Zebras living alone or in "bachelor" (or nonbreeding) herds are rarely approached sexually (or competed for) by either "bachelor" males or herd stallions (both of whom sometimes participate in homosexual activities). Stallions may even actively prevent new females from joining their herds. "Surplus" male Great Cormorants — some of whom form homosexual pairs — never display any interest in the (heterosexually paired) females among them. Conversely, in populations of Orange-fronted Parakeets with an "excess" of females, homosexual pairing is not limited to birds {143} that "can't find" heterosexual mates, since females paired with males also regularly form same-sex bonds (as part of bisexual trios). Adult bull Wapiti often show no sexual interest in females they happen to encounter outside the breeding season (even if the females are in heat at that time), while younger bulls do often show such interest. Yet homosexual activity in this species occurs in both age groups outside the breeding season — and therefore in neither case can it be due to a lack of access to females. Finally, in many Duck species that have a surplus of males, females are swamped by males trying to rape them — but in almost all cases, such males are already paired to females. Unpaired males without access to heterosexual partners rarely, if ever, engage in forced copulations with females (regardless of whether homosexual behavior also occurs in the species).⁵⁴

Even same-sex activity that does have its genesis in the absence of opposite-sex partners — so called situational homosexuality — often shows remarkable longevity and durability, rarely conforming to the stereotype of being "fragile" or liable to disintegrate once heterosexual mates are available. Captive animals that bond sexually with one another when opposite-sex partners are completely unavailable often resist later attempts to "convert" them to heterosexuality. They may even exhibit a longer-term "preference" for same-sex mates that outlasts their initial "situational" introduction to homosexuality. A pair of male White-fronted Amazon Parrots, for example, vigorously refused the advances of female birds even though their homosexual bond was formed "because" no females were available, while two female Long-eared Hedgehogs who were sexually involved with each other in the absence of males refused to mate heterosexually for up to two and a half years after {144} they were separated (as mentioned earlier). The bonding in same-sex pairs of male Steller's Sea Eagles and female Barn Owls (housed without any heterosexual mates) was strong enough to enable successful coparenting of chicks, and in some cases the birds ignored subsequent introductions of opposite-sex partners. Male Rhesus Macaques, Crab-eating Macaques, Bottlenose Dolphins, Cheetahs, and Black-headed Gulls with homosexual bonds resist the attentions of opposite-sex partners or are clearly distressed when separated from one another, and/or they promptly renew their relationship on being reunited — often showing visible signs of affection and excitement when seeing their male partner again. This is also true for male Mallard Ducks that are raised together, in whom homosexual pairing typically becomes their lifetime "orientation." They consistently seek the company of other males even when opposite-sex mates are available and maintain their homosexual bonds year after year (or re-pair with males after the death of a partner) in spite of persistent overtures from females.⁵⁵

The Contamination of Homosexuality
      Of all the scientists who have advocated a shortage explanation for homosexuality, not one has ever specified a critical sex ratio that will consistently "induce" homosexuality, or a crucial threshold of members of the opposite sex that must be present in order to unfailingly prevent individuals from "resorting" to homosexuality. Is a mere 5 percent surplus of one sex enough to tip the scales? Apparently, since a population of Ring-billed Gulls with only 55 percent females is claimed to have enough of a skew to "cause" homosexual pairing. Yet a 5 percent excess of males in other species such as Greylag Geese is apparently not sufficient to "precipitate" homosexual pairing.⁵⁶ In fact, it is highly unlikely that a single critical sex ratio could ever be specified, because the proportion that "causes" homosexuality in one species (or population) has no such effect at all in other species, even where enormous "surpluses" (of, say, 80 percent or more of one sex) are concerned. More broadly, the underlying assumption behind the shortage hypothesis — that sex ratios actually determine a species' mating habits and social systems — has already been shown to be false for other types of mating behaviors. Scientists now recognize that there is not a clear, one-way causal relationship between how many males or females are available in a population, and the form that their mating system takes (e.g., polygamy as opposed to monogamy). Rather, a complex interplay of many factors is at work.⁵⁷ Unfortunately, the subtlety of this interaction is generally only recognized where heterosexual mating systems are concerned.

The shortage hypothesis is not only suspect on theoretical grounds, it is often applied to particular cases in a hasty or inconsistent fashion. Skewed sex ratios in animals exhibiting same-sex activity are often presumed without adequate supporting evidence, or else questionable "explanations" are proposed for the origin of such skewed ratios.⁵⁸ This is best illustrated by the species in which the shortage explanation is most prominent: Gulls. In the late 1970s and early 1980s scientists noticed that high levels of DDT and other environmental contaminants seemed to be associated with some populations of Western and Herring Gulls where nests {145} contained supernormal clutches (often belonging to lesbian pairs). The following chain of "causation" was proposed to explain the apparent correlation: toxins (such as DDT) cause "feminization" of male Gull embryos, which in turn leads to female-biased sex ratios, which in turn results in lesbian pairs, who then attempt to breed, ultimately laying supernormal clutches.⁵⁹ Let's set aside for the moment the fact that this explanation is only of limited applicability — homosexual pairing is not associated with environmental toxins in over 70 other bird species, including several Gulls (e.g., Ring-billed Gulls, Common Gulls, and Kittiwakes).⁶⁰ Let's also set aside the fact that it is only of limited explanatory value — even if it could be shown conclusively that same-sex pairing results from skewed sex ratios that in turn result from toxins, the fact that only some species (and only some individuals in each species) respond to such conditions with homosexuality would still need to be addressed. Even for the Gull species where this explanation is supposedly relevant, however, each link in the overall chain is weak.

First, although laboratory experiments have shown that some toxins may cause male bird embryos to develop some ovarian tissue, no "feminized" male chicks or adults have actually been found in the wild among Western Gulls (or other species) living in contaminated areas.⁶¹ Second, it is unlikely that toxin-induced feminization of males would result in populations with more breeding females than males (since it is most definitely not the case that toxins actually "convert" male embryos into female birds with fully functional ovaries). It would have to act either directly on the health of males, causing more deaths, or indirectly, by resulting in behavioral changes in males that would prevent them from mating with females. But there is no direct evidence that toxins cause anything beyond some physiological alterations in the reproductive organs of Gulls.⁶² A higher mortality rate among males exposed to toxins has never been demonstrated, nor have behavioral differences among such males been observed that might lead them to forgo mating or otherwise to be "unavailable" as mates.⁶³ It has been suggested that "chemically sterilized" males simply fail to join the breeding colonies, or that such males are "no longer interested" in copulating heterosexually. Yet this begs the question of how or why sterility (or other physiological modifications) causes such males to exempt themselves from reproductive activities, or what exactly prevents them from pairing (or even copulating) with females even if they are sterile. Just because an animal is intersexed or transgendered (e.g., "feminized") does not necessarily mean that it is asexual or that its reproductive organs or behavior are "dysfunctional." "Masculinized" female Deer, Bears, and Spotted Hyenas, for example, regularly mate with males, give birth, and raise offspring — even though such individuals often have highly modified reproductive anatomies and hormonal profiles. Even when they are sterile, transgendered and intersexual animals in other species engage in courtship, copulation, and/or pair-bonding. Thus, it is overly simplistic to equate changes in reproductive physiology with an absence of sexual, pairing, or even procreative abilities. It should also be pointed out that a skewed sex ratio is not necessarily an "unnatural" result of environmental contamination: many Gull populations are in fact "naturally" biased in favor of females independently of the effects of toxins, owing to the overall higher survival rate of females (among other factors).⁶⁴
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Regarding the third link in this proposed chain: skewed sex ratios do not in fact automatically result in homosexual pairs — some populations of Western and Herring Gulls with a disproportionate number of females, for example, have few (if any) same-sex pairs.⁶⁵ Even in populations that do have a surplus of females, only a subset of the birds actually form homosexual pairs: most unpaired female Herring Gulls remain single (lesbian pairs constitute less than 3 percent of all pairs, and sometimes as few as 1 in 350), and some males remain unpaired even in populations with more females than males (indicating that some "extra" females are bypassing heterosexual mates). Granted, scientists were able to "induce" the formation of female pairs in a population of Ring-billed Gulls by removing males. However, this simply demonstrates that many females in this species have a latent bisexual capacity that manifests itself when males are in short supply — not that all same-sex pairs in this (or any other species) result from a shortage of the opposite sex. Moreover, the sex ratio that was required to "trigger" homosexual pairing (77 percent females) was much higher than the proportion of females in naturally occurring populations with homosexual pairs (55 percent females).⁶⁶ Apparently not all bird species have this latent bisexual capacity either (or at least not to the same extent), since homosexual pairing does not occur in most species that have their sex ratios experimentally manipulated. Removing males (or adding females) to populations of willow ptarmigans, bufflehead ducks, Pied Flycatchers, great tits, Brown-headed Cowbirds, and song, seaside, and savanna sparrows, for example, results in females mating polygamously with males or remaining single (among other strategies) rather than forming same-sex pairs. When alternate heterosexual behaviors such as polygamy are "induced" in usually monogamous species such as these, scientists do not interpret this as evidence that the behavior is somehow "artificial" or that its occurrence is due solely to the experimentally triggered demographic changes. Rather, it is taken to indicate that the species possesses an inherent capacity for polygamy (and more broadly, a flexibility of mating behavior), perhaps expressed at relatively low levels in most populations but manifesting itself on a larger scale under the appropriate conditions.⁶⁷ Significantly, this interpretation has not generally been afforded homosexual pairing.

Fourth, the evidence for homosexual pairing as a breeding strategy is slim. According to scientists, females bond with same-sex partners in order to raise young that result from copulation (but not pairing) with males (since two-parent care is generally required in these species). However, only a relatively small proportion of females in homosexual pairs actually mate with males and lay fertile eggs: 0-15 percent of Western Gull eggs belonging to female pairs are fertile, while only 4-30 percent of Herring Gulls' are fertilized, indicating that few such females are actually breeding.⁶⁸ Most importantly, females that could potentially benefit from same-sex pairing — were it a reproductive strategy — do not generally "avail" themselves of this option. Researchers found that unpaired Herring Gull females that copulate with males do not in fact go on to form homosexual pairs in order to raise any resulting offspring, nor do they even try to form such pairs. Likewise, Ring-billed Gull, Western Gull, and Roseate Tern mothers that have lost their male partners (and are otherwise unable to find another male) do not establish same-sex {147} pair-bonds with available females, even though they supposedly need to find a new mate to assist them with parenting. In addition, some unpaired and homosexually paired Ring-billed females may actually lay eggs in the nests of other (heterosexual) pairs. This shows that: (a) single females need not seek pair-bonding (with birds of either sex) in order to have their young raised by two parents, and (b) at least some females in homosexual pairs lay eggs that they have no intention of caring for themselves.⁶⁹

Lastly, there is not an absolute correlation between female pairs and supernormal clutches. True, in some species most lesbian pairs lay supernormal clutches, and most supernormal clutches belong to lesbian pairs. However, in many cases female pairs lay "normal"-sized clutches (or lose eggs so they end up with regular-sized clutches), while oversized clutches also regularly result from many other factors. These include egg stealing or adoption, supernumerary clutches laid by one female, nest-sharing by two heterosexual pairs, egg laying by outside females (not paired to the nest owners), and heterosexual trios, among others. In many gulls and other species, the connection between supernormal clutches and homosexual pairs has never been established (e.g., glaucous-winged gulls) or has been refuted (e.g., black-tailed gulls, brown noddies). Hence, studies that show correlations between toxins and increases in supernormal clutches cannot reliably be extrapolated to homosexual pairing unless it has been independently established that female pairs in that species lay larger than average clutches.⁷⁰

Scientists also frequently point out a "correlation" between the two end points of this chain — toxins and supernormal clutches — without also providing evidence for all the intervening links.⁷¹ To show conclusively a relationship between the two phenomena, all the intermediate sequences need to be established, and they should preferably be established for the particular species in question. Sometimes, extrapolations are made in these links between species: that is, toxins are shown to be in the environment of one Gull species, feminization from toxins in another Gull species, skewed sex ratios in a third, female homosexual pairs in a fourth, and supernormal clutches in others — yet rarely (if ever) have all these conditions been shown to coexist in the same species or geographic area.⁷² Moreover, in many Gull studies this chain is collapsed entirely or rendered circular. If homosexuality occurs in a species, and there is also evidence of contamination or pollutants in the environment, the two are automatically assumed to be linked. Homosexual pairing is regarded as a self-evidently "dysfunctional" phenomenon (typically characterized as "reproductive failure"), hence investigators often feel no need to address the actual details of occurrence or causation in the supposed link to toxins. Indeed, the very existence of homosexuality is often subtly equated with environmental contamination and disease even when no actual pollutants have been discovered in the population in question. Ultimately, female pairing is seen as more than simply a behavioral response to certain demographic parameters, which may or may not be indirectly traceable to certain chemical effects. Rather, it assumes the status of a pathological "symptom" directly induced by man-made toxins, symbolizing the larger havoc that people have wreaked on the environment — nature gone awry as a result of human meddling.⁷³ In the end, homosexuality becomes not merely the result of {148} pollution, but the very "contamination" that is itself poisoning otherwise healthy — that is, purely heterosexual — species.

In summary, then, unavailability of the opposite sex is, at best, a tenuous "explanation" for the occurrence of animal homosexuality. Aside from having questionable theoretical and methodological underpinnings, this explanation is in many cases simply incompatible with the facts. In other cases, while same-sex activity does occur in contexts where opposite-sex partners are unavailable, many additional factors are involved, and many important questions concerning its occurrence remain to be addressed. Why, for example, do only some individuals or species with sex-skewed populations exhibit homosexual activity, while others manifest a wide variety of alternative behavioral responses? And why have social systems that entail sex segregation or skewed sex ratios — and hence that supposedly "favor" homosexual activities — evolved in the first place, and in so many species? Where it is relevant, unavailability of the opposite sex should be seen as only one of many contributing factors — and the beginning of further study of other more complex issues surrounding the occurrence of homosexuality in animals. Unfortunately, this explanation continues to be offered as a final scientific pronouncement on the "cause" of same-sex activity. Not only does this do a disservice to the actual richness of animal behavior, it effectively discourages further investigation of a phenomenon whose true intricacies are just beginning to be understood.

"The Errors of Their Ways" — Homosexuality as Mistaken Sex Identification

One surprisingly common scientific "explanation" for the occurrence of animal homosexuality is that it simply results from an inability on the part of animals to "properly" differentiate males from females, or else it represents an "indiscriminate" mating urge (i.e., any perceived differences between the sexes are ignored). This explanation is common for some "lower" animals such as insects and amphibians, where there is limited evidence that mating may indeed be random between homosexual and heterosexual.⁷⁴ However, this type of "indiscriminatory" mating or mistaken sex identification has also been proposed for higher animals, including more than 55 mammals and birds — mostly species in which adult males and females superficially resemble each other (e.g., Cliff Swallows), or in which adolescent or juvenile males supposedly resemble adult females (e.g., Blackbucks, Birds of Paradise).

The gist of this explanation is that when animals engage in homosexuality they are just "making a mistake" — they intend to mate heterosexually, but simply misidentify the sex of their partner because of the physical resemblance between the sexes. Indeed, homosexual interactions are explicitly labeled as "mistakes" or "errors" in several species. Male Cock-of-the-Rock who mount other males have actually been described as "confused" and "bumbling"; the "aberrant sexual behavior" of male Giraffes who mount each other is attributed to their "muddled reflexes"; Black-billed Magpies are characterized as "confused" when they engage in "misdirected" courtship activity with birds of the same sex; and one scientist even {149} suggested that same-sex courtship in Mountain Sheep would probably never occur if males could properly distinguish females from young males.⁷⁵ Often, the very existence of homosexuality in a species is taken to be "proof" that the animals cannot distinguish males from females: "In many waders the sexes are difficult to distinguish, not only to the observer, but on occasions to the birds themselves, as records of males attempting to copulate with other males have been recorded." The circularity in this line of reasoning is blatant, since usually no further evidence is offered to indicate that sex misrecognition is prevalent in the species.⁷⁶ Conversely, the absence of homosexuality in species such as yellow-eyed penguins and its infrequency in Silvery Grebes and Red-faced Lovebirds is offered by scientists as evidence that there are no "problems" with sex recognition in these species.⁷⁷

Bumbling and Confused?
      Quite clearly, sex misrecognition cannot be a widespread "cause" of homosexuality in animals. Same-sex courtship, copulation, and/or pair-bonding occur in numerous species in which males and females look very different from each other: many primates and hoofed mammals, for example, and birds as varied as Ostriches, Grouse, Black-rumped Flameback Woodpeckers, and Scottish Crossbills, to name just a few. Conversely, homosexuality is not found in many animals in which males and females are visually indistinguishable. For example, same-sex activities are not reported for any of the 31 species of North American perching birds in which younger males significantly resemble adult females, while homosexuality occurs in only a small fraction of the hundreds (if not thousands) of birds in which adult males and females are identical to each other.⁷⁸ Moreover, in the majority of species where homosexuality is attributed to mistaken sex identification, only one sex is involved in homosexual activity (usually males). If the animals truly could not tell males and females apart, we would expect both sexes to participate in homosexuality at comparable rates — unless, of course, only one sex has trouble identifying the other, which seems improbable. Furthermore, in many species where homosexual interactions between adult and adolescent males are attributed to the resemblance of the younger males to females, homosexuality also occurs between adults or older males, or between females, where sex misrecognition is not likely. This is true for Blackbucks, Mountain Goats, Elephant Seals, Bishop Birds, Swallow-tailed Manakins, and Superb Lyrebirds, among others. Adult-adolescent homosexuality also occurs in many species where younger males do not resemble females, or between females (where neither partner specifically resembles a male).

In some mammals and birds where homosexuality is attributed to the resemblance between younger males and adult females (e.g., Blackbucks, Manakins, Birds of Paradise), the two sexes are not necessarily identical. Rather, older adolescent and younger adult males exhibit physical characteristics that are actually intermediate between those of adult females and adult males, and they are often recognizably male.⁷⁹ Even in species where homosexuality is claimed to result from the identical appearance of males and females, there are often slight but noticeable physical differences between the sexes that may be discernible to individuals. These include {150} body and horn size in Mountain Goats, wing length in Bishop Birds (with juvenile males distinct from adult females), iris color and other aspects of eye structure in Galahs, relative size and other body measurements in Humboldt and King Penguins, patterning of tail feathers in male and female (and between adult female and juvenile male) Superb Lyrebirds, wing and tail length (and, in some populations, wing feather notching) in Ocher-bellied Flycatchers, presence of a brown forehead patch and shorter wings in female Tree Swallows, and bill structure and tail coloration between adult female and juvenile male Anna's Hummingbirds.⁸⁰

Are these (often subtle) differences actually perceptible to the animals themselves? Implicit in many scientists' pronouncements of sex misrecognition is the assumption that just because males and females look alike to our eyes, they must be indistinguishable to the animals as well. Species differ widely in their visual acuity, color perception, and other sensory abilities, so each case needs to be evaluated individually before any conclusions can be made about animals' sex recognition abilities — and this has most definitely not been systematically investigated for cases involving animal homosexuality. Nevertheless, one thing is certain: we are only beginning to understand many aspects of animal perception, including heretofore unimagined powers of visual, acoustic, and temporal recognition. Scientists recently discovered, for example, that a number of birds such as starlings, Zebra Finches, bluethroats, and Blue Tits use ultraviolet vision in distinguishing between individuals and between sexes. Birds that appear identical in ordinary light have different patterns under UV that are recognized and used by other members of their species to choose mates. Likewise, males and females of some butterfly species that are indistinguishable to us have radically different appearances in UV light. In the acoustic and temporal realms, analysis of tape recordings of Lyrebird vocal mimicry has revealed that their perception of time may be ten times greater than that of humans, giving them the extraordinary ability to imitate the calls of five different birds simultaneously.⁸¹ It is quite likely, then, that animals can perceive {151} differences in appearance or other minute sensory cues that are distinguishable only to human measuring instruments and not to human eyes (or ears).

Further evidence that animals can differentiate between males and females that appear identical to us comes from the different frequencies of homosexual and heterosexual interactions in species with "indistinguishable" sexes. Animals often preferentially court, mate, or bond with individuals of one or the other sex. Male Mountain Goats. for example, court male yearlings more frequently than female yearlings even though they are supposedly "unable" to differentiate between the two. The opposite scenario occurs in Musk-oxen: although adult males court both yearling males and females, they interact with females more than with males. Likewise, Dwarf Cavy adult males court juvenile males more often than they do juvenile females (and even seek out specific male partners). In contrast, adult males in the closely related Aperea court only juvenile females and never males, even though in both of these species juvenile males and females are purportedly indistinguishable. Among Bighorn Sheep, rams are claimed to be sexually interested in other males in direct proportion to how closely the latter resemble females — yet yearling males, which resemble females the most, still receive far less sexual attention than do females, indicating that some form of sexual differentiation still occurs. Although male Common Murres are said to mount other males because they have difficulty distinguishing the sexes, females are still mounted at a much higher rate than males. Supposedly "indiscriminate" sexual chases by male Flamingos actually involve many more pursuits of females than males. Finally, adult male Pronghorns court and mount yearling and two-year-old males, both of whom superficially resemble females. However, adults actually direct more sexual behavior toward two-year-olds, who are as "femalelike" as (if not more "malelike" than) yearlings in terms of the size of their horns and black cheek patches.⁸²

A related argument against sex misrecognition as a factor in precipitating homosexuality is that males and females are often behaviorally distinct even when they are physically identical. A male who "looks like" a female will frequently perform identifiably male behavior patterns during a homosexual interaction, seriously casting doubt on the notion that his partner has failed to recognize his actual sex. Male Antbirds "mistaken" for females actually initiate and reciprocate courtship feeding with their male partners (something females never do). Younger male Swallow-tailed Manakins and Regent Bowerbirds that participate in courtship with adult males may physically resemble females, but they exhibit distinctly "masculine" behaviors, displays, or vocalizations. Among male Greenshanks, both participants in homosexual copulations display in a typically male fashion prior to same-sex mounting, and both female partners in Jackdaw homosexual pairs preen each other (a typically female activity). There is hardly a more identifiably "male" activity than copulating with a female, yet male Laughing Gulls sometimes make sexual advances toward males who are in turn mating with their female partners (creating a three-bird "pile-up"). Nor are such homosexual mounts simply attempts by the topmost male to mate with the female, since he often remains mounted on the other male (or continues to remount him repeatedly) even after the female becomes "available" once her partner dismounts. Conversely, there is {152} hardly a more definitively "female" activity for birds than laying eggs, yet male Black-headed Gulls have been observed bypassing females in the very act of laying an egg in order to try to copulate with her male partner!⁸³ It seems highly unlikely that homosexual activity in a case such as this is due to faulty sex recognition (especially since heterosexual copulation attempts on laying or incubating females are fairly routine among Gulls), yet this is a prominent "explanation" for same-sex behavior in this species.

Deceptively Clear
      In many animals where only a subset of the population resembles the opposite sex (or is transgendered), the occurrence of homosexuality is often directly counter to what would be expected if confusion between the sexes were "causing" homosexual behavior. For example, adolescent male Scottish Crossbills resemble females in their plumage coloration, yet homosexual pairs in this species form between adult males, not between adult and juvenile males. In Ruffs, some males resemble females in that they lack the elaborate neck feathers and other distinctive plumage characteristics of other males, yet homosexuality in this species is not limited to these "naked-nape" males. Males who do not resemble females also court and mount each other, while "femalelike" males often mount more "masculine" males. Tree Swallows are unusual among North American perching birds in that females retain the drab gray-brown plumage of adolescence during the first year that they breed, making them resemble adolescent males more than adult females. Thus, one would expect that either (a) adult males would be more apt to "mistake" brown-plumaged females for males, perhaps responding more aggressively to them (i.e., as if they were males); or (b) homosexuality in this species would manifest itself as an age-based system, with males pursuing only younger brown-plumaged males because they "mistake" them for first-year breeding females. Neither of these scenarios is true, however: males have no trouble recognizing the sex of brown-plumaged females (and in fact are significantly less aggressive toward them), and homosexuality in this species involves adult males interacting with each other, not adults being "confused" by brown-plumaged males.⁸⁴

Black-headed Gull males and females are nearly identical in appearance, except that males have, on average, slightly longer heads and bills than females. However, some males are more "femalelike" in that they have shorter head and bill lengths than average. If sex misrecognition were operative in this species, one would predict that smaller males (i.e., birds who more closely resemble females in size) would be more likely to form homosexual pairs (since males would "mistake" them for females) and less likely to form heterosexual pairs (since females would "mistake" them for other females). On the contrary, scientists studying sex recognition in this species found that female-resembling males are just as likely to form heterosexual as homosexual pair-bonds. In fact, smaller males are more successful at maintaining long-lasting heterosexual bonds and fathering chicks than more "masculine"-appearing males — paralleling other cases of greater heterosexual prowess in some transgendered animals.⁸⁵
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Other species in which both transgender and homosexuality occur are particularly cogent examples of how ineffective sex misrecognition is in "explaining" homosexuality. Typically, the patterns of same-sex and opposite-sex interactions in these species do not follow the clear divisions that would be expected if individuals were simply "mistaking" their partners for the opposite sex. In Hooded Warblers, for example, some females have transvestite plumage, appearing almost identical to males because of their dark hoods (which are usually found only in males). Others have intermediate plumage, darker or more melanistic than most females but without the complete hood pattern of males, while others have no "malelike" head feathers at all. Males, though, are typically heavier and have longer wings than females, hooded or otherwise. It has been suggested that male homosexual pairs initially form in this species because of the visual resemblance between some females (transvestites) and males. Yet if males in homosexual pairs tended to confuse hooded females with males, one might expect them to pair with individuals whose sex is especially "blurred" or hard to decipher: darker, more malelike females and/or smaller, more femalelike males. However, at least one bisexual male chose just the opposite kinds of mates. His male partner did not have female body proportions but, on the contrary, was exceptionally "masculine" in this regard, exceeding the average weight and wing lengths of most males. Conversely, his heterosexual pairings involved "obviously" female partners, i.e., nontransvestite or only moderately melanistic individuals. Moreover, males that are supposedly mistaken for females in homosexual pairings do not develop brood patches (a distinctive bare patch of skin on the belly used for incubating eggs, characteristic only of females). So it is unlikely that such males are mistaken for hooded females.⁸⁶ There is also evidence that male Hooded Warblers do not generally confuse transvestite or melanistic females with males. First of all, males are differentially aggressive toward other males, attacking them during territorial encounters more often and ignoring them less often than they do the darkest, most malelike females. Furthermore, "masculine-appearing" (melanistic) females are generally as successful as nontransvestite females in finding male partners and are as subject to promiscuous copulation attempts by males as are nontransvestite females.⁸⁷ If males tended to confuse hooded females with males, they would probably avoid darker birds (including melanistic females) during heterosexual mating interactions (since such birds would more likely be other males), yet this does not appear to be the case.
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Even in species where some individuals clearly are "tricked" into same-sex relations by transgendered animals, the situation is considerably more complex than this. In Common Garter Snakes, for example, some males produce a pheromone that is similar to the scent of females. These individuals are called she-males by scientists, and they attract as many male suitors as female snakes do. Most males who court she-males are apparently "deceived" into thinking they are interacting with a genetic female. However, she-males and genetic females are not identical: chemical analysis has shown that the pheromones of she-males, rather than being indistinguishable from those of females, are actually intermediate between those of males and females. When given a choice, most nontransvestite males prefer genetic females — demonstrating that they can distinguish between the two under the appropriate circumstances. Moreover, nontransvestite males sometimes abandon their courtship of females to pursue she-males, and up to 20 percent of males may actually prefer courting she-males rather than females when given a choice — indicating that not all individuals who interact with transgendered snakes do so entirely under "false pretenses." Even though their pheromones resemble females', she-males also have no trouble finding opposite-sex partners — in fact, some studies indicate that they may be more successful in mating with females than males who are not transvestite (she-males actually have more than three times as much testosterone as do males). In addition, male Garter Snakes also occasionally court each other in situations that do not appear to involve transvestism — and therefore not all same-sex interactions can be attributed to (transgender-induced) mistaken sex identification. In many other species where a subset of the population is transgendered, homosexuality does not occur at all, and transgendered individuals again have no difficulty in attracting mates of the opposite sex. This is true for female red-winged blackbirds that have malelike epaulets, female Pied Flycatchers that have the white forehead patches characteristic of males, female lesser kestrels that have male rump and tail coloration, and younger male long-tailed manakins whose plumage resembles that of females.⁸⁸ If sex misrecognition were a "cause" of homosexual pairing, one would expect same-sex pairing, courtship, or mounting to be prevalent in these species as a result of "confusion" between transvestite individuals and members of the opposite sex. One would also expect transvestite individuals to be avoided by members of the opposite sex because they do not resemble "obviously" heterosexual partners. Once again, neither of these scenarios generally occurs.

Another problem with attributing homosexual interactions to mistaken sex identification is that it can (at most) account for the initial interest of one animal in another of the same sex. It cannot explain why the animal "mistaken" for the opposite sex often willingly participates in the homosexual interaction or may even initiate it. Even if homosexual pairs in Antbirds, for example, result from an initial failure on the part of a courting male to distinguish between the sexes (as has been claimed), such pairs could not persist for years unless both males were actively fostering the bond between them (or at the very least, not resisting the homosexual relationship). As scientists studying homosexual matings in Tree Swallows have pointed out, even if males mistake other males for females (which is not likely), the {155} males they copulate with nevertheless do not resist their homosexual advances and even actively facilitate genital contact. Notably, they do not adopt the specific tactics used by birds in this species to deter unwanted sexual advances (typically displayed by females in heterosexual contexts). While male Black-crowned Night Herons may court males and females indiscriminately, their male partners are nevertheless sexually stimulated by the performance and may go on to form a homosexual pair-bond with them. In Regent Bowerbirds, "female-resembling" adolescent males may actually initiate courtship display toward adult males (the reverse of the usual scenario in cases of "mistaken" sex identification). Finally, male Greenshanks who visit other males' territories and are "mistaken" for females actively precipitate homosexual courtship pursuits: they depart from the territory using a special swerving flight pattern that invites the other male to follow them (also used by females during heterosexual courtships). If they did not want to spark a homosexual courtship, they could simply employ any of the several strategies used by females to deter males' advances in this species, such as leaving the territory in a direct flight path or "leapfrogging" over a pursuing male during a ground chase — yet these are not typically part of homosexual interactions.⁸⁹ Thus, even if mistaken sex recognition is responsible for bringing two animals of the same sex together, it is ultimately irrelevant in explaining why those two animals often remain together to continue their interaction and bring it to its full conclusion, be it a completed courtship or mating episode, or a pair-bond lasting many years.⁹⁰

In summary, a whole host of considerations cast serious doubt on mistaken sex recognition or indiscriminate mating as an explanation with wide applicability (or credibility). Once again, the complexities of animal behavior elude the broad brushstrokes of human interpretation. Numerous interconnected elements must be factored in, such as the subtleties of actual physical differences between the sexes, the strength and acuity of animals' various perceptual abilities, differential behaviors between males and females, the active participation of individuals "mistaken" for the opposite sex, and the intricacies that arise when transgender is layered over homosexuality. In the end, the most significant "misrecognition" is probably not that of animals who overlook each other's sex, but that of scientists who fail to recognize the importance and interplay of these factors. Nevertheless, even if mating or courtship in some species is in fact random or indiscriminate between males and females, such "randomness" is actually compelling evidence (once again) for a bisexual capacity in such creatures. This in itself is a vital observation that is frequently downplayed by scientists, who all too readily discount the homosexual part of this mating equation as a necessary "error" made by animals on their path to achieving greater heterosexual output. In such a mechanistic view, animals simply mate with as many partners as they can — male or female — to maximize their reproductive success, even if it means that some of their matings will be nonreproductive. The fact remains, however, that such animals have the ability to respond sexually to individuals of their own sex — and they do so repeatedly, with apparent enthusiasm, and (one might add) noticeable disregard for the "mistakes" they are making.
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"Gross Abnormalities of Behavior" — Homosexuality as Pathology

Homosexuality in animals has frequently been regarded as a pathological condition. Such terms as abnormal and aberrant are routinely applied to this phenomenon (as mentioned in chapter 3), often with no further justification or explication — homosexuality is considered sufficient in itself to warrant the label of disease, disorder, dysfunction, or deviance. A number of researchers, however, are more specific in their pathologizing of homosexuality and transgender, and in this section we'll examine two of the principal "explanations" of this sort that have been put forward: the claims that homosexuality is caused by the artificial conditions of captivity, and that homosexuality/transgender is the manifestation of a physiological abnormality.

Something Amiss at the Zoos
      For a long time, scientists discounted examples of animal homosexuality because some of the earliest descriptions were based on captive animals. In many cases, biologists continue to classify this behavior as "abnormal" and attribute it to the "unnatural" circumstances of confinement or contact with humans. One scientist, for example, writes of homosexual pairs in Swans (as well as other "sexual aberrations" such as heterosexual trios and interspecies matings): "Captive swans, like many other animals, sometimes show gross abnormalities of behavior. These are due almost entirely to the artificial conditions under which the birds are kept."⁹¹ As recently as 1991, homosexuality in Wattled Starlings was ascribed to their captivity. Other species for which similar "explanations" have been proposed (including appeals to factors such as crowding and/or stress in captivity) include Common Chimpanzees, Gorillas, Stumptail Macaques, Musk-oxen, Koalas, Long-eared Hedgehogs, Vampire Bats, and Black-crowned Night Herons.⁹² Sometimes the only context where same-sex activity is discussed is to exemplify the types of "pathologies" that arise in captivity. Homosexuality in Dolphins, for instance, was offered as an illustration of the "sexual aberrancy" that can result from confinement in aquariums, while a case of female coparenting in Barn Owls was included in a report on "Abnormal and Maladaptive Behavior in Captive Raptors" — part of a monograph on (of all things) diseases in birds of prey. Homosexual activity in Rhesus Macaques was even presented (along with a number of other "abnormal" behaviors) as an illustration of the deleterious effects of malnutrition.⁹³ In a perfect example of the sort of circular reasoning that is employed in many scientific discussions, homosexuality in captive animals is often cited as the "proof" of the artificiality of their captive conditions. One zoologist proclaims, "Homosexual behavior [in Cheetahs] ... is reported in zoos as quite frequent, which to me indicates that something is amiss at the zoos," while another states, "The very occurrence of female-female pairs [in Zebra Finches] suggests behavioral pathology."⁹⁴ This is chillingly reminiscent of the not-so-distant "medicalized" views of human homosexuality, where the mere existence of same-sex attraction or activity was sufficient to "diagnose" pathology or mental illness.
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While it is true that captivity sometimes does induce unusual behaviors in animals, the bulk of the evidence does not support this as a "cause" of animal homosexuality. As primatologist Linda Fedigan observes, "Although ... homosexual relationships in animals can occur as a result of stressful captive conditions, we would suggest that all such behavior should not be dismissed as pathological or dysfunctional, a practice which results in 'explaining it away' rather than explaining it."⁹⁵ On statistical grounds alone there is no substantiation for a greater incidence of homosexuality in captive animals — in fact, just the reverse is true. In more than 60 percent of the mammals and birds in which same-sex activity has been documented, this behavior occurs spontaneously in the wild. In more than two-thirds of these species, homosexuality has only been observed in the wild, while in the remaining cases it occurs in both wild and captive animals.⁹⁶ A number of scientists have remarked on a higher rate of homosexual activity in captivity compared to in the wild when the behavior occurs in both situations. In other words, there may be a quantitative, rather than qualitative, difference between wild and captive conditions, although the occurrence of homosexuality itself cannot be attributed to confinement. However, even this difference is less than clear-cut. In some species such as Orang-utans, Hamadryas Baboons, Mule Deer, and Musk-oxen, there does indeed appear to be a higher rate of homosexual courtship and/or sexual activity — as well as heterosexual activity — in captivity compared to the wild, although in some instances this is based on impressionistic observations.⁹⁷ In contrast, two species for which detailed quantitative information is available show nearly identical rates of same-sex activity in the wild versus captivity: in Bonobos, studies of wild animals have revealed that 45-46 percent of all sexual activity is homosexual, while a captive study yielded a figure of 49 percent; in Black Swans, one investigator found that 5 percent of captive pairs were homosexual while 6 percent of wild ones were.⁹⁸

Failure to observe homosexuality in the wild is more often due to incomplete study or inadequate observational techniques rather than an actual absence of the behavior in free-ranging animals. Time and again, same-sex activity has initially been seen only in captive animals and therefore declared to be definitively not a part of the "normal" sexual repertoire of the species in the wild. Yet when detailed field studies of the same species are finally conducted — often decades later — homosexuality is inevitably discovered. In fact, so pervasive or routine is the behavior now known to be for some species in the wild, that scientists have had to completely revise prior assessments of same-sex activity as "artificial" for these animals in captivity. In Bottlenose Dolphins, for example, male pairs engaging in homosexual behavior were originally observed in aquariums and were considered to be the "aberrant" result of keeping males together without females. Detailed longitudinal and demographic studies of the species — more than forty years later — revealed that male pairs, as well as sex segregation, are a prominent feature of the social organization of this species in the wild. By 1998, zoologists were actually advocating that captive male Bottlenose Dolphins be kept (and reintroduced into the wild) as bonded pairs, recognizing that these constitute a "natural functional social unit" of the species that can assist captive individuals in adjusting to life in the wild upon their release. Another example of a complete turnaround on the part of scientists{158} concerns Gorillas. Early studies of this species reported that homosexuality was not seen in wild Gorillas; three decades later, extensive same-sex activity had been documented in both males and females in the mountain forests of Africa. By 1996, biologists and zookeepers were (at last) openly acknowledging that homosexuality in all-male groups was not an "artificial construct of captivity," and were even encouraging the formation of such groups in zoos to approximate the species' natural social patterns.⁹⁹

Many other examples of field studies confirming earlier captive observations of homosexuality (and disproving initial assessments of its "artificiality") can be found. In 1935, Konrad Lorenz asserted that the formation of same-sex pairs in female Jackdaws "does not appear to occur under natural conditions"; it wasn't until more than forty years later that ornithologists confirmed the occurrence of homosexual pair-bonding in wild Jackdaws. Same-sex activities between male Elephants in captivity were first reported in the scientific literature in 1892 and characterized as "aberrations" and "perversions"; almost 75 years later, similar and more extensive homosexual interactions were documented among wild Elephants. In 1997 zoologists presented the first descriptions of same-sex activities in wild Crested Black Macaques, finally confirming captive observations made more than thirty years earlier. Because no detailed field studies of this species had been conducted before the 1990s, all prior reports of homosexual activity were based on observations in captivity, leading some scientists to suggest that same-sex activity was not likely to be found in wild Crested Black Macaques — a prediction we now know was incorrect. Homosexual pairing in Parrots was long considered to be "induced or brought forth by the conditions of confinement," but in 1966 an ornithologist documented a male pair of Orange-fronted Parakeets in the forests of Nicaragua — the first confirmation of homosexuality in wild Parrots. Ironically, the sex of the birds was verified only because the scientist mistook them for a heterosexual pair copulating unusually early in the breeding season (and therefore he wanted to check the condition of their internal reproductive organs). Initial observations of homosexuality in captive female Lions, made in 1942, were confirmed in the wild in 1981, while observations of male pairs in wild Great Cormorants in 1992 corroborated early observations of this phenomenon among zoo birds in 1949. Likewise, same-sex courtship in Regent Bowerbirds was first described on the basis of aviary observations in 1905, but display between wild males was not documented until nearly a century later. And homosexual activity between different species of Dolphins, long observed in aquariums, was finally verified in a wild population in 1997.¹⁰⁰ Today, homosexuality in many species is still known only from captive studies, but it is likely that most, if not all, of these will follow this same pattern and eventually be confirmed by field studies. Perhaps it is finally time for scientists to acknowledge that homosexuality in captive animals is nearly always an expression of their normal behavioral repertoire, rather than a result of their captivity.

Another point to keep in mind is that the distinction wild versus captive is in some sense a false dichotomy, since in actuality there is a continuum of degrees of confinement, "artificiality," and human intervention in the living conditions of animals. At one extreme are truly "wild" animals that have experienced no, or virtually {159} no, contact with humans — an increasingly rare phenomenon in the contemporary world. At the other extreme are domesticated animals that have been bred and raised in captivity for many generations, often to the point of being genetically distinct (as a separate species or subspecies) from their wild counterparts. In between, there is a whole spectrum of contexts and factors. Toward the more "wild" end of the continuum, there are free-ranging species that have nevertheless experienced varying degrees of human contact or interference, such as Killer Whale populations that have been heavily poached, or wild Tree Swallows that nest in colonies of human-supplied nest boxes, or Grizzly Bears living in "disturbed" habitats, or wild Atlantic Spotted Dolphins that are habituated to the presence of people.¹⁰¹ There are also semi-wild animals, a cover term that includes a host of different situations. For instance, unconfined animals may nevertheless be tame (e.g., Greylag Geese), while animals on reserves may be wild or "free-ranging" within a confined but extensive territory, often hundreds or thousands of acres in size (e.g., Bison, Cheetahs). Transplanted populations consist of entire troops or herds that have been moved, their social organization and demographics intact, to a new (often more restricted) environment, sometimes because they are endangered in their natural habitat (e.g., Rhesus Macaque troops transplanted from India to Puerto Rico, Blackbuck herds moved from India to France). Another semi-wild situation involves animals that are recently extinct in the wild and therefore can only be observed in captivity (e.g., Takhi, Pere David's Deer). In many cases such species are kept in conditions that approximate their "former" wild habitat and social organization as closely as possible, and in some instances they are even being slowly reintroduced to the wild from their captive populations. "Provisioned" animals are wild but supplied with food and varying amounts of human contact (e.g., Japanese Macaques), while "rehabilitated" animals are formerly captive (and possibly wild-born), but reintegrated into wild populations (e.g., Orang-utans). Finally, feral species are domesticated animals that have escaped and "gone wild," establishing their own free-ranging populations (e.g., Water Buffalo, Mute Swans, Rock Doves).

Among captive animals, a wide variety of factors — each of which represents a continuum of its own — must also be considered when assessing the "artificiality" of their confinement: Are the animals wild-born or raised in captivity? Are they tame and/or trained, or do they have little or no contact with humans? Are they free-ranging within an outdoor enclosure (e.g., at a zoo or wild-animal park) or are they kept in restrictive cages (e.g., in a laboratory)? Are they living in mixed-sex groups or sex-segregated groups — and which is typical of wild populations? How closely does their social organization in captivity approximate that of wild animals, in terms of the size and number of social groups, the sex and ages of the animals making up those groups, and the transiency or stability of such groups? With regard to the occurrence of homosexuality, virtually every situation along this continuum — and every semi-wild context — has been claimed to be "artificial" to one degree or another, or else "natural" enough not to warrant concern. Yet the fact that homosexuality has been observed in virtually every one of these contexts argues for the relative independence of this behavior from whatever conditions of "captivity" or "wildness" may prevail. Moreover, what constitutes a "natural" captive context is {160} often directly counter to preconceived ideas. Regarding Cheetahs, for example, a number of researchers have commented that keeping males and females together in captivity is actually something of an "artificial" situation (since it seems to contribute to an inhibition of heterosexual courtship and mating); conversely, same-sex pair-bonds appear to be integral to the "psychosocial well-being" of males. Ironically then, sex segregation in captivity is actually more "natural" for this species, since it reflects the Cheetah's social organization in the wild (a situation that is also true for many other species in which males and females typically live apart from each other).¹⁰²

It should also be pointed out that something of a double standard exists regarding what is interpreted as "natural" as opposed to "captivity-induced" behavior. It is common zoological practice, for example, to study mate choice in pair-bonding species (such as birds) by setting up captive situations where individuals are only given a "choice" of opposite-sex partners. It is also standard practice to keep zoo animals strictly in heterosexual pairs for breeding purposes. Thus, a sizable portion of reported "heterosexual" behavior is in fact based on situations that would be considered "artificial" if they were used to study homosexual behavior. In other words, if animals are kept only with members of their own sex and then subsequently exhibit homosexual activity, this is overwhelmingly interpreted as "situational" behavior that would not otherwise happen. In contrast, if they are only given access to opposite-sex partners and subsequently exhibit heterosexual behavior, this is without exception interpreted as an expression of their "natural" tendencies. Although researchers readily regard homosexuality to be the result of external or artificial factors operating on otherwise heterosexual animals, no one has dared suggest that the reverse situation might also sometimes occur — that heterosexuality could be "forced" on otherwise homosexual (or largely same-sex-oriented) animals. In fact, zoos and other captive breeding programs offer countless reports of animals "failing" to breed in captivity for no apparent reason when placed with opposite-sex partners. Even after exhausting the long list of factors that could be involved, animal breeders uniformly overlook the possibility that some of these individuals may simply have a preference for same-sex activities and/or partners.

In the majority of species where homosexuality has only been observed in captive or semi-wild conditions, researchers have confirmed that other aspects of behavior or social organization in captivity — including sexual behaviors — are comparable to those of wild animals. In some instances, behaviors once considered to be "abnormal," "artificial," or "unusual" products of captivity have also been documented in the wild. For example, Botos frequently play with man-made objects in aquariums (carrying and manipulating rings, brushes, and so on) and also interact playfully with animals of other species kept in their tanks. Wild Botos have also been observed in similar behaviors, playing with sticks, logs, fruit pods, and even fishermen's paddles, as well as with other species such as river turtles. Tool use and manufacture by Orang-utans had long been known from studies of captive and semi-wild animals, but until the behavior was documented in wild Orang-utans in 1993, it was considered typical only of "artificial" situations. One researcher, studying {161} captive Savanna Baboons, asserted that "certain types of behavior such as copulation during pregnancy or lactation may be related to caged life, and not be the norm in natural populations," yet later studies of wild populations revealed that these behaviors do in fact occur regularly. Likewise, until it was documented in the wild, cross-species herding behavior by male Thomson's Gazelles was thought to be caused by the unavailability of same-species groupings in captivity. Parenting trios, mate-switching, promiscuous copulations, and egg stealing were all initially observed in captive King Penguins and considered to be "unusual" (if not "abnormal") behaviors. Yet detailed study of this species in the wild nearly thirty years later verified the occurrence of each one of these activities, as well as many other "unexpected" behavioral patterns. In a few cases, a more "unusual" behavior has only been documented in wild populations, or else is more prevalent in the field than in captivity: for example, reverse mounting in Black-headed Gulls and divorce in Flamingos.¹⁰³ Thus, while homosexuality has not yet been observed in many of these species in the wild, it is probably only a matter of time before it is.

Other situations involving homosexuality in captive animals also occur. Often same-sex activity in one species has only been observed in captivity (e.g., Siamangs, Mute Swans, Sociable Weavers), yet a closely related animal does exhibit similar or identical behavior in the wild (e.g., White-handed Gibbons, Black Swans, and Gray-capped Social Weavers, respectively). In other cases, one form of homosexuality is seen in captivity and another form in the wild. In Griffon Vultures, for example, homosexual pairs and sexual activity have been observed in captivity while same-sex courtship and pair-bonding display flights have been seen in the wild. In Emus, sexual activity between males has been documented in captivity and male coparenting in the wild. In Galahs, homosexual pairs have been observed extensively in captivity but not in the wild, although "supernormal clutches" — nests with double the number of eggs, typical of female pairs in other birds — have been verified in the field. And in Cheetahs, same-sex courtship and sexual activity have been seen in captivity while male pair-bonds have been observed in both wild and captive animals. This suggests that the absence of certain behaviors in studies of wild animals are probably accidental "gaps" that will be filled once more extensive field studies are conducted. This is particularly likely when one considers that the proper observational techniques for identifying homosexual activity are often not employed, even in species where same-sex activity has previously been verified in captivity. In the most recent ongoing field studies of Griffon Vultures, for example, the sex of birds is determined "behaviorally" by their position during mounting (top bird = male, bottom bird = female), or not verified at all, thereby precluding the possibility of detecting homosexual pairs. "Behavioral" sexing has also been employed in the major long-running studies of large populations of wild King Penguins, Gentoo Penguins, and Flamingos — in some cases combined with "morphological" sexing, i.e., the larger bird in a pair is assumed to be male and the smaller female, without actual verification of sex — all species in which same-sex pairs have been observed in captivity but not yet documented in the wild. And the sex of wild Dugongs participating in mating behavior has never been unequivocally determined in nearly two decades of field observations; researchers invariably assume {162} that the interactions are heterosexual, even though same-sex activity has been observed in captivity (and in the wild in the related West Indian Manatee).¹⁰⁴

It must also be remembered that it is often extremely difficult to observe some species in the wild or obtain detailed information about their behavior. Many animals in which homosexuality has only been seen in captivity present formidable challenges to field study. Some are nocturnal (active only at night) or crepuscular (active at dusk or dawn), such as Lesser Bushbabies (and other Lemurs), Wolves, Rufous Bettongs, and Black-crowned Night Herons. Others are diurnal (active in the daytime) but engage in sexual behavior mostly at night (e.g., Red Deer). This can greatly hamper efforts to observe sexual activity: homosexual mounting in Red Foxes, for example, was only discovered by setting up remote-control infrared video cameras to continuously monitor nighttime activities in a captive population — virtually impossible to do under field conditions. Other species are highly elusive: Bush Dogs, for example, have rarely even been sighted in the wild, let alone studied, and the most complete analysis of their social organization in captivity was only published in 1996. Likewise, the elusiveness of Pig-tailed Macaques precluded detailed field observations until the early 1990s, while the first in-depth behavioral studies of wild Crested Black Macaques were published in 1997. Sometimes the inaccessibility of the animal's habitat poses nearly insurmountable hurdles: Siamang Gibbons, for example, frequent the jungle canopy as much as 120 feet above the ground, and homosexuality in the closely related, and equally arboreal, White-handed Gibbon was not discovered in the wild until 1991. Whales and Dolphins spend less than 20 percent of their time at the surface of the water, and underwater observation (where sexual activity often occurs) is frequently impractical.¹⁰⁵ This is compounded by the fact that recognition of individual animals and determination of their sex — essential for obtaining detailed behavioral data — is also usually extremely difficult. An animal's size can also be a factor: few behavioral observations of wild Apereas have been made because they are so small and their social activities {163} are often hidden in dense grass and brush. Small size (among other factors) also hampers field observations of Squirrel Monkeys, Rufous-naped Tamarins, and Rufous Bettongs. The latter species is also largely asocial or solitary, a problem encountered as well in Bears and numerous other carnivores, where many thousands of hours of observation in the field often yield precious little information about social or sexual interactions.

Even for species that are not difficult to observe, enormous time must still be invested in observation and quantification of behaviors before a reasonably complete picture of the animals' habits can be pieced together. Zoologists have estimated that to obtain a good working understanding of a species, three field-workers would need to invest two years and 2,000 hours of observation time — yet even this may not be enough. Over a dozen scientists studying Orang-utans, for example, have collectively spent more than ten times this amount — 20 years and a combined total of 22,000 hours of field observation — yet they admit that many aspects of the behavior of this species are still poorly understood. Likewise, zoologists involved in a comprehensive study of Oystercatcher behavior in the wild did not observe homosexual activities until nearly a decade into their research project.¹⁰⁶ It's no wonder, then, that many behaviors, including homosexuality, are just beginning to be documented in the wild or have yet to be observed outside of captivity. In summarizing wild versus captive comparisons of animal behavior, Jane Goodall has remarked, "If a primate shows behavior in captivity which has not been observed in the wild, this by no means implies that it does not occur in the wild."¹⁰⁷ The history of the study of animal homosexuality has shown this to be a truism, not just for primates, but for all species.

Hormonal Imbalances and Other Monstrosities
      Unable to find any other "reason" for same-sex activity in animals, many scientists have tried to argue that homosexuality is itself a physical abnormality or the manifestation of some pathological condition. The most common physiological "malfunctions" that are suggested to "explain" homosexual behavior in animals are some sort of hormonal imbalance, and an "abnormal" condition of the sex organs. Female Sage Grouse who court and mount other females are described as suffering from "hormonal or hermaphroditic irregularities," for example, while scientists speculate on the "endocrine balance" of female Rhesus Macaques that participate in homosexual activity, the possible "hormonal defects" of female Fat-tailed Dunnarts that mount other females, and the influence of "abnormal physiological particulars" on the lesbian behavior of Long-eared Hedgehogs. Scientists have even suggested that homosexual mounting by Takhi mares who are pregnant is due to the male hormones circulating in their system as a result of carrying a male fetus.¹⁰⁸

Scientific studies of homosexuality often seek evidence of "irregularities" in the form or condition of an animal's sex organs. This reflects in large part the widespread misconception (stemming from early sexological discussions of humans) that homosexuality is tantamount to hermaphroditism — i.e., any gender "transgression" is mapped onto an anatomical or physiological "abnormality." In 1937, {164} scientists carefully examined the external genitalia of a male Common Garter Snake that had engaged in sexual behavior with another male to verify that it had "normal" male sex organs (it did). They then killed and dissected the animal to see if it had female gonads, reporting "no ovarian tissue was discovered." Lest one think this merely reflects the outmoded views of the time, nearly 60 years later this scenario was repeated with uncanny parallelism. In 1993 scientists performed a laparotomy (a surgical technique to examine the internal sexual organs) on a male Hooded Warbler that repeatedly formed homosexual pairs, in order to verify its sex and determine the condition of its male organs; the bird was later killed to obtain tissue samples. They reported that his sex organs were indistinguishable from other males', adding — in words echoing those used more than half a century earlier — "No ovarian tissue was present."¹⁰⁹ Just as early medical descriptions of homosexuality in humans often focused attention on the supposedly abnormal development or condition of the external genitals (along with hormonal factors), so, too, have scientists studying same-sex activity in animals tried to link this behavior to genital "peculiarities." In describing male companions in African Elephants, one zoologist emphasized that animals in such partnerships may exhibit physical "defects" including "enlarged external genitalia," while an ornithologist describing a male Snow Goose in a homosexual pair felt compelled to remark, "His much enlarged penis indicated a strong endocrine stimulation."¹¹⁰

There is no evidence to support a hormonal or other physiological "explanation" of animal homosexuality, and there is considerable evidence against it. Comprehensive and rigorous endocrinological analyses, as well as gonad measurements, of homosexual Western and Ring-billed Gull females show conclusively that there are no significant hormonal or anatomical differences between birds in homosexual and heterosexual pairs that could account for same-sex pairing. Specifically, investigators found that females in homosexual pairs are not hormonally "masculinized," i.e., they do not have higher levels of male hormones (androgens) than do females in heterosexual pairs. If anything, homosexual females may be more hormonally "feminine" than heterosexual females: some lesbian Ring-billed Gulls actually have significantly higher levels of progesterone, a female hormone associated with nest-building and incubation behavior.¹¹¹ Likewise, studies of a variety of primate species have shown no correlation between hormone levels and homosexual activity.¹¹²

Conversely, researchers have found hormonal differences between individuals in some species that exhibit homosexual behavior, but not in animals that participate specifically in same-sex activity. Endocrinological studies of Pied Kingfishers, for example, reveal that some males have lowered testosterone levels (as well as smaller gonads), but these individuals constitute one class of nonbreeding "helpers" who assist their parents in raising young. Few, if any, such males are involved in the homosexual pair-bonding or mounting activity that sometimes occurs in this species. Likewise, a certain category of nonbreeding Orang-utans (those with "flanges") often have elevated estrogen levels — but homosexual activity is neither characteristic of, nor exclusive to, such individuals. In other species scientists have determined that an "unusual" hormonal profile is found in the majority of {165} individuals, but this is not linked to homosexual activity. In Spotted Hyenas, females generally have higher levels of a particular "male" hormone (a type of androgen) than do males, yet only a fraction of them actually participate in same-sex mounting; moreover, pregnant females also have elevated levels of testosterone (regardless of the sex of their fetus) but are not more prone to same-sex mounting. Likewise, all female Western Gulls have high levels of androgens (including testosterone) — nearly equal to those of males — regardless of whether they are in homosexual or heterosexual pairs.¹¹³ These examples illustrate another important point: in many species a portion of the population routinely exhibits hormonal profiles (or other physiological characteristics) that differ from the "norm" — sometimes correlated with nonbreeding — yet only when individuals display overt homosexuality or transgender is the label of abnormality or dysfunction applied.

In most instances where a physiological "explanation" is advocated, this is purely conjectural, not based on any actual hormonal studies of the animals involved, and often highly improbable on independent grounds. For example, the connection between male fetal hormones and a pregnant mother's behavior — advocated as an "explanation" for mounting among female Takhi — is entirely speculative, since endocrinological profiles were not drawn up for the specific individuals involved in same-sex activity. Moreover, even if there were a connection, it would be at most only a partial explanation for this (and other) species. One Takhi mare mounted males when carrying a male fetus rather than mounting other females and also failed to show similar behavior the next year when she was again pregnant with a male fetus.¹¹⁴ Thus, additional factors must be involved in determining whether such mares participate in homosexual, bisexual, and/or heterosexual (reverse) mounting behavior, if any of these. More generally, this explanation does not have wide applicability to other species. For example, only a fraction of Domestic Horses (which are closely related to Takhi) ever show mounting behavior of any sort when pregnant.¹¹⁵ In addition, homosexual behavior by pregnant females occurs in less than 8 percent of all mammals in which female homosexual mounting has been documented, and in none of these species is the behavior exclusive to pregnant females (or to pregnant females carrying male fetuses). A fetal hormonal "explanation" is irrelevant, as well, for huge segments of homosexual activity, such as same-sex behaviors in animals that do not get pregnant (males of virtually all species and females of egg-laying species, for example).

In addition to being empirically unfounded, physiological explanations are also suspect on conceptual grounds. Almost without exception, hormonal or other pathological accounts of homosexuality focus on the animal exhibiting "gender-atypical" behavior, e.g., the male being mounted or the female doing the mounting. The partners of these individuals are usually considered to be physically "normal" animals whose behavior warrants no further consideration. Yet in many cases the "gender-conforming" partners are equally active participants in homosexual activity, sometimes even initiating same-sex interactions. As we saw in the discussion of "pseudoheterosexual" explanations, this categorization of animals into gender-conforming versus nonconforming, or "truly homosexual" versus "not-quite-homosexual" individuals, is in most cases arbitrary. It reflects not so much any {166} inherent qualities or meaningful behavioral attributes in the animals themselves, but rather the observer's biases or conceptual categories.¹¹⁶

The pathologizing of "gender-atypical" behavior is taken to its extreme in the discussion of transgendered animals. Early descriptions of intersexual animals of ten labeled them "monstrosities."¹¹⁷ More recently, hermaphroditism, chromosomal and other forms of gender mixing, and physical and behavioral transvestism are invariably considered diseased states, birth defects, physiological abnormalities, or otherwise dysfunctional. Yet researchers have usually been as unsuccessful in determining the physical "causes" for transgender as they have for homosexuality. For example, in discussing what they call "effeminate" behavior in Bighorn rams (males who exhibit some of the behavioral and social characteristics of females), scientists have tried to appeal to hormonal factors. Yet they were forced to conclude that this is an unsatisfactory explanation, since such males are physically "normal" and differ from other rams only in their behavior. The entire discourse surrounding transgender in White-tailed Deer centers on describing this as a "pathological condition" and attempting to find its physiological source. Velvet-horns (gender-mixing male deer) in Texas were subjected to a comprehensive battery of tests, including sampling and dissection of their sex organs to look for infection or "anomalies," blood tests for possible microorganisms or contaminants, dietary profiles, hormone injections, and chromosomal studies, none of which turned up any "cause." Investigators finally concluded that this "condition" must be due to a naturally occurring toxin in the soil where the animals live, yet admitted that no specific substance that might have this effect could be pinpointed or isolated in the animals' environment. Similarly, a gender-mixing Savanna (Chacma) Baboon in South Africa was shot and dissected to "study" its reproductive organs. Another was captured and given hormone "treatments" to see if it would behave like a "normal" female (defined, in this case, as participation in heterosexual intercourse with a male). Investigators stated that this individual could have been a "successful female in the wild" if only it had "normal functioning ovaries."¹¹⁸

These cases highlight one of the primary reasons that transgendered animals are usually considered abnormal: they often cannot (or do not) reproduce. Yet this is a limited and erroneous definition of "normalcy" that overlooks crucial facts about the lives of transgendered (and nontransgendered) animals. For one thing, transgendered animals arise "spontaneously" and repeatedly in natural populations, and they do survive successfully in the wild. Gender-mixing Baboons similar to the one given hormonal treatments have been observed in the same area of South Africa as far back as the early 1900s and are probably a regularly occurring feature of this and other populations. Moreover, such individuals are fully integrated members of their troops and may even assume high-ranking or "leadership" positions. The truth is, the gender-mixing individual described above (and others like it) was able to survive and even prosper without "normal functioning ovaries." Similarly, velvet-horns have been reported in a wide range of geographic areas and at least as far back as 1910-20, again indicating a long-standing, regular feature of natural Deer populations.¹¹⁹ Although such individuals are sometimes "ostracized" {167} by other Deer, they have developed their own forms of social organization, living in distinct "communities" with unique behavior patterns.

Conversely, many nontransgendered animals fail to participate in reproduction and may in fact never successfully procreate during their entire lives (numerous examples will be discussed in the next chapter). If failure to reproduce were sufficient grounds to exclude an individual from "normalcy," the majority of animals in some populations and species would not make the roster. In contrast, many transgendered animals do reproduce, such as intersexual Bears and gender-mixing female White-tailed Deer, and may in fact be more heterosexually successful than nontransgendered animals (as in transvestite Northern Elephant Seals, Red Deer, Black-headed Gulls, and Common Garter Snakes¹²⁰). The final irony is that nonbreeding animals (including transgendered individuals) are also sometimes more healthy than breeders, precisely because they do not reproduce. Velvet-horn White-tailed Deer, for instance, are generally in much better physical condition than breeding males because they do not undergo the extreme physical rigors of the rutting season, which often cause severe weight loss and may even stunt growth in young bucks. Likewise, the mortality rate of breeding Bighorn rams is nearly six times higher than that of nonbreeding males. Clearly, then, participation in reproduction can be a liability rather than an asset to an individual's survival and success.

The vehement pathologizing of transgender encapsulates the entire discussion surrounding the "cause" of alternate sexual and gender expression in animals. Phenomena such as homosexuality or gender mixing are never seen as neutral or expected variations along a sexual and gender continuum (or continua), but rather as abnormal or exceptional conditions that require explanation. At the root of this perception is the idea that homosexuality and transgender are dysfunctional behaviors or conditions because they do not lead to reproduction. In the next chapter, we'll explore in greater detail the role of procreation in the animal kingdom and its complex interrelationships with homosexuality, bisexuality, transgender, and heterosexuality. Some of our most fundamental assumptions regarding the significance of reproduction must be revised as we come to understand the often surprising ways that animals structure their breeding and nonbreeding lives.
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