Bruce Bagemihl - Biological Exuberance

Female homosexual mounting also occurs in three other closely related species of antelopes, the Waterbuck, Lechwe, and Puku. Interestingly, Waterbuck females that mount each other are not usually in heat, unlike Kob. Occasionally, a Waterbuck female will perform courtship flehmen with another female as well. Hermaphrodite or intersexual individuals also sometimes occur in Kob: one animal, for example, was chromosomally male and had testes and large horns, combined with a vagina, uterus, and enlarged clitoris.

Frequency: Homosexual mounting is common among Kob. Each female participates in same-sex mounting about twice an hour (on average) during the mating season, and over an entire mating season a female might mount other females 60 or more times (although most females probably engage in this activity a dozen or so times). However, because heterosexual mounting rates are extraordinarily high—more than seven times higher than homosexual rates—same-sex mounting accounts for only about 9 percent of all sexual activity. Homosexual courtship displays are less common than same-sex mounting in this species. In Puku and Lechwe, mounting between females is also common, but it occurs only occasionally among Waterbuck.

Orientation: Most, if not all, female Kob are bisexual, participating in both heterosexual and homosexual mounting, but individuals vary along a continuum in their orientation. For some, same-sex mounting makes up nearly 60 percent of their sexual activity, while for others it constitutes only 1–3 percent, but the average is about 11 percent. Fewer Kob females use courtship displays with other females, but there is a parallel range in variation. About 7 percent of females employ a significant portion of the full courtship repertoire when interacting with other females. In the other species of Kob antelopes, females that engage in homosexual mounting probably also participate in heterosexual activities as well.

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.

*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 für 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 für Tierpsychologie 26:39–47.

Wirtz, P. (1983) “Multiple Copulations in the Waterbuck (Kobus ellipsiprymnus).” Zeitschrift für 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 für Tierpsychologie 58:277–300.

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; Clères Park, Rouen, France.

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.

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.