Biological Exuberance: Animal Homosexuality and Natural Diversity

or shoulders, occasionally developing an erection. Similar courtship behaviors occur among male Asiatic Mouflons.

In addition to genital licking (in Thinhorns), sexual activity between rams usually involves mounting and anal intercourse: typically the larger male rears up on his hind legs and mounts the smaller male, placing his front legs on the other’s flanks. The mountee assumes a characteristic posture known as LORDOSIS, in which he arches his back to facilitate the copulation (this posture is also seen in many female mammals during heterosexual mating). Usually the mounting male has an erect penis and achieves full anal penetration, performing pelvic thrusts that probably lead to ejaculation in many cases. Mounting and courtship interactions between males sometimes also take place in groups known as HUDDLES: three to ten rams cluster together in a circle, rubbing, nuzzling, licking, horning, and mounting each other. Usually huddles are non-aggressive interactions in which all males are willing participants; occasionally, though, several rams in a huddle focus all their attentions on the same (usually smaller) male, taking turns mounting him and even chasing him if he tries to get away. Female Mountain Sheep also occasionally participate in sexual activity with one another, including licking each other’s genitals, mounting, and occasional courtship activities.

A male Bighorn Sheep in the Rocky Mountains mounting another male

So pervasive and fundamental is same-sex courtship and sexuality in Bighorns and Thinhorns that females are said to “mimic” males in order to mate with them. They adopt the behavior patterns typical of younger males being courted by older males, thereby sparking sexual interest on the part of rams because, ironically, they now resemble males. In another twist on gender roles and sexuality, there are also occasionally “female-mimicking” males in some populations—but notably, such males do not typically participate in homosexual mounting and courtship. Transgendered males are physically indistinguishable from other rams, but behaviorally they resemble females. They remain in the sex-segregated ewe herds year-round, they often adopt the crouching urination posture typical of females, and they are lower-ranking and less aggressive than most males and even many females (even though they are often larger in body and horn size, the typical criteria used to establish rank). Most significantly, transgendered rams do not usually allow other males to court or mount them. Again, this is a typically female pattern, since ewes in these species generally do not permit rams to court or mount them except for the few days out of each year when they are in heat.

Frequency: In Bighorns and Thinhorns, homosexual mounting occurs commonly throughout the year, but is especially frequent during the rut when heterosexual activity is also taking place, accounting for about a quarter of all sexual activity at that time (and occurring in up to 69 percent of males’ interactions with each other). Outside of the rut, all mounting activity is homosexual, but mounting only accounts for 2–3 percent of males’ interactions with each other. Among females, 1–2 percent of interactions include mounting. At least 70 percent of males’ interactions with one another involve courtship behaviors. Homosexual activity appears to be less frequent in Asiatic Mouflons: it is seen sporadically in wild animals, while in captivity about 10 percent of mounting and some courtship behaviors occur between animals of the same sex, mostly females. Behavioral transvestism occurs in approximately 5 percent of rams in some populations of Bighorn Sheep.

Orientation: Virtually all male Bighorn and Thinhorn Sheep participate in homosexual courtship and mounting; the extent to which they also engage in heterosexual pursuits during the rut varies with their age and rank. Younger, lower-ranking rams—close to half of the male population— rarely get to mate with females at all, and some of these males have only homosexual relations. Among older, higher-ranking rams, heterosexual behavior is much more common—but even when they are courting and mounting females, it is often because of the malelike behavior patterns that the females are using (as described above). In other words, even in their heterosexuality, Mountain Sheep may be decidedly “homosexual.”

Nonreproductive and Alternative Heterosexualities

Large portions of the male population in Bighorn and Thinhorn Sheep do not breed (as mentioned above). Although many younger and lower-ranking males try to mount females, they are able to mate less than 20 percent of the time because both females and higher-ranking rams will not usually allow them to complete their copulations. However, nonbreeding rams actually have a much lower mortality rate than breeding males—nearly six times lower—owing to the stresses of reproduction (including fasting during the breeding season, fights and chases, and other major energy expenditures). Ewes often reject the advances of older, higher-ranking rams as well (nearly 65 percent of the time in Bighorns), and this may lead to harassment and even forced copulations or rapes. In fact, rams employ three distinct strategies to try to mate with females, only one of which entails courtship and consensual copulations. TENDING involves a ram following a particular female for short periods of time, during which he courts her and is usually permitted to mate. COURSING consists of a ram chasing and sometimes butting a female, who is usually forced to copulate under threat of further punishment from the ram. BLOCKING involves forcefully cornering and trapping females with threats and more violent actions such as horn butts; ewes may be knocked down or bounced against trees if they try to escape and have been sequestered for up to nine days at a time by blocking rams. Almost half of all ewes in heat, on average, experience the trauma of blocking. Rams also sometimes mount lambs as well as females who are not in heat—in all, about 15 percent of heterosexual mounts are on such nonfertilizable partners. Male Mountain Sheep “masturbate” by crouching, protruding the penis sideways past the front legs, and ejaculating (sometimes after nuzzling the penis or rubbing it against the front leg). As described above, Mountain Sheep society is strongly sex-segregated for the majority of the year. Since rams and ewes only associate for two months or so during the rut, females usually raise their young on their own with no help from males. Occasionally, however, a ewe who has lost her own lamb will help another mother suckle her young. Such “helpers” are more common among higher-ranking females, where up to 30 percent of mothers who have lost their lambs may foster-nurse other youngsters.

Other Species

Same-sex courtship and mounting occur in several other species of wild sheep and goats, involving similar behavior patterns to those found in North American and European wild sheep. Among Bharal or Blue Sheep (Pseudois nayaur) of the Himalayas, 36–57 percent of mounting occurs between males (sometimes in huddles), while approximately 11 percent of courtship displays such as the low-stretch, twist, and foreleg kick are performed between males. Males also perform a “penis display” toward other males, in which the animal sometimes licks or sucks his own organ. Male Markhor (Capra falconeri) and Wild Goats or Bezoar (Capra aegagrus), two Central Asian species, also occasionally court and mount other males, as do male and female Aoudad or Barbary Sheep (Ammotragus lervia) of North Africa.

Sources

*asterisked references discuss homosexuality/transgender

*Berger, J. (1985) “Instances of Female-Like Behavior in a Male Ungulate.” Animal Behavior 33:333-35.

Demarchi, D. A., and H. B. Mitchell (1973) “The Chilcotin River Bighorn Population.” Canadian Field-Naturalist 87:433–54.

Festa-Bianchet, M. (1991) “The Social System of Bighorn Sheep: Grouping Patterns, Kinship, and Female Dominance Rank.” Animal Behavior 42:71–82.

*Geist, V. (1975) Mountain Sheep and Man in the Northern Wilds. Ithaca, N.Y.: Cornell University Press.

*———(1971) Mountain Sheep: A Study in Behavior and Evolution. Chicago: University of Chicago Press.

*———(1968) “On the Interrelation of External Appearance, Social Behavior, and Social Structure of Mountain Sheep.” Zeitschrift fur Tierpsychologie 25:199–215.

*Habibi, K. (1987a) “Behavior of Aoudad (Ammotragus lervia) During the Rutting