Biological Exuberance: Animal Homosexuality and Natural Diversity

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 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

A herd of male Gray Seals hauled out on land during the molting period on Ramsay Island (England). Just before this picture was taken, the two bulls at the water’s edge near the large rock were engaging in homosexual activity-a common pursuit among males of all ages at this time of year. Although a few females may be present in these spring haul-outs, they are largely ignored by the males, demonstrating that their homosexual activity is not simply a “substitute” for heterosexual mating.