What’s Good for the Goose … : Comparisons of Male and Female Homosexuality
Is homosexuality more characteristic of male animals or female animals? And does it assume different forms in the two sexes—or, to paraphrase a popular saying, is the behavior of the “goose” essentially similar to that of the “gander”? As it so happens, homosexuality in three species of Geese—Canada, Snow, and Greylag—exemplifies some of the major patterns of male and female homosexuality and the range of variation found throughout the rest of the animal world. In Canada Geese, both males and females participate in the same basic type of homosexual activity, forming same-sex pairs and engaging in some courtship activities. Within these same-sex bonds, however, there are gender differences in some less common behaviors: sexual activity is more characteristic of females (especially if they are part of a bisexual trio), as is nest-building and parenting activity. There are also differences in the frequency of participation of the two sexes: although same-sex pairs are relatively common, accounting for more than 10 percent of pairs in some populations, a greater proportion of the male population participates in same-sex pairing. In contrast, homosexual activity in Snow Geese is vastly different in males than in females, although it is relatively infrequent in both sexes. Females form long-lasting pair-bonds with other females in which sexual activity is not necessarily very prominent, although parenting activity is: both partners lay eggs in a joint nest and raise their young together (they fertilize their eggs by mating with males). Ganders, on the other hand, limit their homosexual activity to same-sex mounting of other males during heterosexual group rape attempts and do not form same-sex pairs (although interspecies gander pairs with Canada Geese sometimes do occur). Finally, in Greylag Geese homosexual activity is found exclusively in males, who form gander pairs that engage in a variety of courtship, sexual, pair-bonding, and parenting activities.
When we look at the full range of species and behaviors, we find that male homosexuality is slightly more prevalent, overall, than female homosexuality, although the two are fairly close. Same-sex activity (of all forms) occurs in male mammals and birds in about 80 percent of the species in which homosexuality has been observed, and between females in just over 55 percent of these (the figures add up to more than 100 percent because both male and female homosexuality are found in some species). It must also be kept in mind that the prevalence of female homosexuality may actually be greater than these figures indicate, but has simply not been documented as systematically owing to the general male bias of many biological studies.19 There is also variation between different animal subgroupings: in carnivores, marsupials, waterfowl, and shorebirds, for example, male and female homosexuality are almost equally common (in terms of the number of species in which each is found), while in marine mammals and perching birds male homosexuality is more prevalent. And in many species same-sex activity occurs only among males (e.g., Boto, a freshwater dolphin) or only among females (e.g., Puku, an African antelope).
The frequency of same-sex behavior in males versus females can also be assessed within a given species, and once again, many different patterns are found: in Rhesus Macaques, Hamadryas and Gelada Baboons, and Tasmanian Native Hens, for example, 80—90 percent of all same-sex mounting is between males, while homosexual activity is also more prevalent among male Gray-headed Flying Foxes.20 In other species, female homosexual activity assumes prominence: more than 70 percent of same-sex copulations in Pukeko are between females, and 70—80 percent of homosexual activity in Bonobos is lesbian. Females account for almost two-thirds of same-sex behaviors in Stumptail Macaques and Red Deer, while homosexual activity is also more typical of females in Red-necked Wallabies and Northern Quolls.21 In some species, however, male homosexuality is so predominant that same-sex activity in females is often missed by scientific observers or rarely mentioned (e.g., Giraffes, Blackbuck, Bighorn Sheep), while the reverse is true in other species (e.g., Hanuman Langurs, Herring Gulls, Silver Gulls). In contrast, Pig-tailed Macaque same-sex mounting, Galah pair-bonds, and Pronghorn homosexual interactions are fairly equally distributed between the two sexes (although actual same-sex mounting is more common in male Pronghorns).22
As with the species of Geese mentioned above, gender differences are also apparent in various behavior types. Of those mammal and bird species in which some form of homosexual behavior occurs, each of the activities of courtship, affectionate, sexual, or pair-bonding are generally more prevalent in male animals. They occur among males in 75—95 percent of the species in which they are found, while among females these activities occur in 50—70 percent of the species (again, however, the possible gender bias of the studies these figures are based on must be kept in mind). The one exception is same-sex parenting, which is performed by females in more than 80 percent of the species where this behavior occurs, but by males in just over half of the species that have some form of such parenting. Of course, not all these forms of same-sex interaction always co-occur in the same species, and animals sometimes differ as to which activities males as opposed to females of the same species tend to participate in (as in the Geese). In Silver and Herring Gulls, for example, females form same-sex pairs that undertake parenting duties while males engage in homosexual mounting; in Cheetahs and Lions, both sexes engage in sexual activity, but males in each species also develop same-sex pair-bonds while female Cheetahs participate in same-sex courtship activities. In Ruffs, males engage in sexual, courtship, and (occasional) pairing activity with each other, while Reeves (the name for females of this sandpiper species) participate primarily in sexual activity with one another.
Within each of the categories of courtship, sexual, pairing, and parenting behaviors, further gender distinctions can be drawn. Consider various types of sexual behavior. Mounting as a same-sex activity is ubiquitous and occurs fairly regularly in both males and females (although there are exceptions—in African Elephants, for example, sexual activity between males assumes the form of mounting while female same-sex interactions consist of mutual masturbation). Oral sex (which includes activities as diverse as fellatio, cunnilingus, genital nuzzling and sniffing, and beak-genital propulsion) is about equally prevalent in both sexes. Group sexual activity is more common in males (only occurring among females in 6 species, including Bonobos and Sage Grouse), as are interactions between adults and adolescents (only occurring among females in 9 species, including Hanuman Langurs, Japanese Macaques, Ring-billed Gulls, and Jackdaws, but among males in more than 70 species). Although penetration is also more typical of male homosexual interactions, there are notable exceptions (e.g., Bonobos, Orang-utans, and Dolphins, as mentioned previously). Gender differences sometimes also manifest themselves in the minutiae of various sexual acts. Same-sex mounting in Gorillas, for instance, is performed in both face-to-face and front-to-back positions, but the two sexes differ in the frequency with which these two positions are used: females prefer the face-to-face position, adopting it in the majority of their sexual interactions, while males use it less often, in only about 17 percent of their homosexual mounting episodes.23 In contrast, the frequency of full genital contact during homosexual copulations is nearly identical for both sexes of Pukeko: females achieve cloacal contact in about 23 percent of their same-sex mounts while males do so in about 25 percent of theirs (in comparison, genital contact occurs in a third to half of all heterosexual mounts). Among Flamingos, though, genital contact is more characteristic of copulations between females than between males.24