Biological Exuberance: Animal Homosexuality and Natural Diversity

Nonreproductive and Alternative Heterosexualities

As described above, Kob society is sex-segregated, and there are large numbers of nonbreeding animals, particularly among males. Only a relatively small proportion of males (about 5 percent) have access to lek territories at one time, and only some of these will be selected by females to mate with. In some populations of Waterbuck, large numbers of males are also nonbreeders: at any given time, only 7 percent of males are territory holders, 9 percent are satellites, and the remainder live in bachelor herds. In fact, only 20 percent of males in this species become territorial during their lives. Although a few satellite and bachelor males mate with females, the majority do not. Female Kob usually mate repeatedly with their chosen males—generally many more times than is required to become pregnant—and may copulate with up to nine different males when they visit the lek. Waterbuck females also mate repeatedly when in heat, usually with the same male each time. Kob heterosexual copulations are often preceded by numerous nonreproductive mounts in which the male does not have an erection. Furthermore, full penetration may not occur during copulation, and often the male does not ejaculate even when he does achieve penetration. Waterbuck males sometimes mount females from the side or other positions where penetration cannot occur. When all types of mounts are considered, the rate of heterosexual activity in Kob is staggering: during a 24-hour visit to the lek, each female may engage in several hundred mountings, 40 of which will be full copulations. Female Lechwe are often chased and harassed by males (especially nonterritorial ones) trying to mate with them. Sometimes several males will disrupt a heterosexual copulation, and only 8 percent of matings in cosexual herds and 42 percent on leks result in ejaculation.

Sources

*asterisked references discuss homosexuality/transgender

Balmford, A., S. Albon, and S. Blakeman (1992) “Correlates of Male Mating Success and Female Choice in a Lek-Breeding Antelope.” Behavioral Ecology 3:112–23.

*Benirschke, K. (1981) “Hermaphrodites, Freemartins, Mosaics, and Chimaeras in Animals.” In C. R. Austin and R. G. Edwards, eds., Mechanisms of Sex Differentiation in Animals and Man, pp. 421–63. London: Academic Press.

Buechner, H. K., J. A. Morrison, and W. Leuthold (1966) “Reproduction in Uganda Kob, with Special Reference to Behavior.” In I. W. Rowlands, ed., Comparative Biology of Reproduction in Mammals, pp. 71–87. Symposia of the Zoological Society of London no. 15. London: Academic Press.

Buechner, H. K., and H. D. Roth (1974) “The Lek System in Uganda Kob.” American Zoologist 14:145–62.

*Beuchner, H. K., and R. Schloeth (1965) “Ceremonial Mating Behavior in Uganda Kob (Adenota kob thomasi Neumann).” Zeitschrift fur Tierpsychologie 22:209–25.

*DeVos, A., and R. J. Dowsett (1966) “The Behavior and Population Structure of Three Species of the Genus Kobus. Mammalia 30:30–55.

Leuthold, W. (1966) “Variations in Territorial Behavior of Uganda Kob Adenota kob thomasi (Neumann 1896).” Behavior 27:214–51.

Morrison, J. A., and H. K. Buechner (1971) “Reproductive Phenomena During the Post Partum-Preconception Interval in the Uganda Kob.” Journal of Reproduction and Fertility 26:307–17.

Nefdt, R. J. C. (1995) “Disruptions of Matings, Harassment, and Lek-Breeding in Kafue Lechwe Antelope.” Animal Behavior 49:419–29.

Rosser, A. M. (1992) “Resource Distribution, Density, and Determinants of Mate Access in Puku.” Behavioral Ecology 3:13–24.

*Spinage, C. A. (1982) A Territorial Antelope: The Uganda Waterbuck. London: Academic Press.

———(1969) “Naturalistic Observations on the Reproductive and Maternal Behavior of the Uganda Defassa Waterbuck Kobus defassa ugandae Neumann.” Zeitschrift fur Tierpsychologie 26:39–47.

Wirtz, P. (1983) “Multiple Copulations in the Waterbuck (Kobus ellipsiprymnus).” Zeitschrift fur Tierpsychologie 61:78–82.

———(1982) “Territory Holders, Satellite Males, and Bachelor Males in a High-Density Population of Waterbuck (Kobus ellipsiprymnus) and Their Associations with Conspecifics.” Zeitschrift fur Tierpsychologie 58:277–300.

BLACKBUCK

IDENTIFICATION: A medium-sized gazelle; males have distinctive spiral horns and a black-and- white coat; females and juvenile males are tan colored. DISTRIBUTION: India; vulnerable. HABITAT: Semidesert to open woodland. STUDY AREAS: Kanha National Park, Madhya Pradesh, India; Cleres Park, Rouen, France.

THOMSON’S, GRANT’S GAZELLES

IDENTIFICATION: Smaller gazelles (2—3 feet at shoulder height) with ringed, slightly S-shaped horns in both sexes; Thomson’s have a conspicuous black flank band, and Grant’s horns may bend sharply outward. DISTRIBUTION: East Africa, especially Kenya, Tanzania, Sudan. HABITAT: Grassy steppes. STUDY AREAS: Serengeti National Park and Ngorogoro Crater, Tanzania; subspecies G.g. robertsi, the Wide-horned Grant’s Gazelle.

Social Organization

Blackbucks live in small, same-sex herds containing 10–50 individuals. Female herds circulate within the territory of one or several adult males who mate with them; the remaining males live in “bachelor” herds on the periphery of the breeding territories. Thomson’s and Grant’s Gazelles have a similar social organization, except that mixed herds containing both males and females also form, especially during migration.

Description

Behavioral Expression: The majority of male Blackbucks have homosexual interactions: among all age groups, mounting of one male by another occurs in the position used for heterosexual intercourse. Usually mounting happens during play-fighting—friendly sparring matches with erotic overtones, sometimes involving three males at a time. In addition, adult males often perform courtship displays toward adolescent males (one-to-two-year-olds) prior to mounting them. These displays, which also occur in heterosexual interactions, begin with the older male DISPLAY WALKING: he stands some distance away from the object of his attentions, lowering his ears and curling his tail up to touch his back. He walks in this posture parallel to the younger male so that the younger one has to walk in a circle. This is followed by PRESENTING THE THROAT: the older male raises his nose high in the air so that his spiral horns touch the back of his neck. This exposes the striking black-and-white pattern of his neck. While doing this, he briskly kicks first one foreleg, then the other, in front of him several times in a row, sometimes reaching under the other male’s belly or between his thighs. Occasionally, the older male makes a distinctive barking sound as he does this. This is then followed by mounting of the younger male by the older. Occasionally, female Blackbucks mount other females.

A male Blackbuck mounting another male during a bout of play-fighting

In Thomson’s Gazelles, male homosexual mounting may occur in a variety of contexts, including during migration and in encounters between two nonterritorial males. Males also occasionally direct courtship displays toward one another, including the NECK-STRETCH, FORELEG KICK, and NOSE-UP POSTURE, as well as the PURSUIT MARCH (the latter similar to heterosexual courtships). Homosexual courtship displays are preceded by one or both males displaying their horns to the other (often interpreted as a threatening gesture). Homosexual