Biological Exuberance: Animal Homosexuality and Natural Diversity

sessions each season, spending about 10 percent of his time in this activity; however, some males may be involved in as many as seven or eight sessions and devote more than 18 percent of their time to this behavior. Overall, in some populations more than three-quarters of observed sexual activity occurs between males.

Orientation: Anywhere from one-third to more than one-half of all males engage in homosexual interactions. This behavior is especially prevalent among younger Orcas: adolescent males participate four times more often than adults. Many males that engage in this behavior are probably bisexual, since they also court and mate with females. However, there are clear differences between individual males in their affinity or “preference” for homosexual interactions: some Killer Whales participate often and actively seek out male partners, while others are much less involved.

Nonreproductive and Alternative Heterosexualities

Orca communities contain a sizable population of older, nonbreeding females. With an average life span of 50 years—and a possible maximum longevity of 80 years—female Killer Whales can experience a postreproductive period of up to 30 years. In some populations, one-third to one-half of adult females are postreproductive, and it is estimated that a stable population can support as many as two-thirds postreproductive females. Many such females are the matriarchs of their group, and their leadership continues even if it means the ultimate demise of the pod: if there are only male offspring, a pod will eventually disappear upon the death of its matriarch, since there are no breeding females to continue the matriline. Many postreproductive females, while not breeding themselves, act as “baby-sitters” or helpers in an elaborate communal parenting system. They, along with breeding females, nonbreeding adult and adolescent females, and adult males, frequently take care of calves when their mothers are away or attending to a sibling. Since most breeding females reproduce only once every five years, there is a large pool of potential helpers who are not themselves parents in the population. It is estimated that each calf may be baby-sat as often as once a day during particularly busy times. Although postreproductive females no longer procreate, they may still participate in sexual activity, often with younger males. Several other types of nonprocreative heterosexuality also occur among Orcas: pregnant females have been observed engaging in courtship and sexual behavior with males, while heterosexual interactions also occur between adults or adolescents (of both sexes) and youngsters (juveniles as well as calves). Some incestuous sexual activity has also been documented, for example between an adolescent male and his juvenile sister. Finally, heterosexual interactions do not always involve just two individuals—sometimes a trio of two males and a female will engage in courtship activity together, and one male may even touch and hold the female while the other copulates with her.

Other Species

Same-sex activity occurs in several other species of toothed whales. Pairs of male Sperm Whales (Physeter macrocephalus) that may be homosexually bonded occur in some populations. In the waters surrounding New Zealand, for example, 3–5 percent of males are found in such pairs, probably belonging to a semiresident population. These male couples travel together closely and are usually composed of two adults or one older and one younger male. Sexual interactions leading to orgasm also take place in groups of (primarily younger) male Sperm Whales off the coast of Dominica. Homosexual activity has been seen in captive male Beluga Whales (Delphinapterus leucas) as well. In addition, hermaphrodite individuals occasionally occur in Belugas and possibly also in Sperm Whales. One Beluga, for example, had male external genitalia combined with a complete set of both male and female internal reproductive organs (i.e., two ovaries and two testes).

Sources

*asterisked references discuss homosexualityltransgender

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*Balcomb, K. C. III, J. R. Boran, R. W. Osborne, and N. J. Haenel (1979) “Observations of Killer Whales (Orcinus orca) in Greater Puget Sound, State of Washington.” Unpublished report, Moclips Cetologi-cal Society, Friday Harbor, Wash.; 46 pp. (available at National Marine Mammal Laboratory Library, Seattle, Wash.).

*De Guise, S., A. Lagace, and P. Beland (1994) “True Hermaphroditism in a St. Lawrence Beluga Whale (Delphinapterus leucas).” Journal of Wildlife Diseases 30:287– 90.

Ford, J. K. B., G. M. Ellis, and K. C. Balcomb (1994) Killer Whales: The Natural History and Genealogy of Orcinus orca in British Columbia and Washington State. Vancouver: UBC Press; Seattle: University of Washington Press.

*Gaskin, D. E. (1982) The Ecology of Whales and Dolphins. London: Heinemann.

*———(1971) “Distribution and Movements of Sperm Whales (Physeter catodon L.) in the Cook Strait Region of New Zealand.” Norwegian Journal of Zoology 19:241-59.

*———(1970) “Composition of Schools of Sperm Whales Physeter catodon Linn. East of New Zealand.” New Zealand Journal of Marine and Freshwater Research 4:456– 71.

*Gewalt, W. (1976) Der Weisswal, Delphinapterus leucas [The Beluga]. Wittenberg: A. Ziemsen-Verlag

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*Haenel, N. J. (1986) “General Notes on the Behavioral Ontogeny of Puget Sound Killer Whales and the Occurrence of Allomaternal Behavior.” In B. C. Kirkevold and J. S. Lockard, eds., Behavioral Biology of Killer Whales, pp. 285–300. New York: Alan R. Liss.

*Jacobsen, J. K. (1990) “Associations and Social Behaviors Among Killer Whales (Orcinus orca) in the Johnstone Strait, British Columbia, 1979–1986.” Master’s thesis, Humboldt State University.

*———(1986) “The Behavior of Orcinus orca in the Johnstone Strait, British Columbia.” In B.C. Kirkevold and J. S. Lockard, eds., Behavioral Biology of Killer Whales, pp. 135–85. New York: Alan R. Liss.

Martinez, D. R., and E. Klinghammer (1978) “A Partial Ethogram of the Killer Whale (Orcinus orca L.).” Carnivore 1:13–27.

Olesiuk, P. F., M. A. Bigg, and G. M. Ellis (1990) “Life History and Population Dynamics of Resident Killer Whales (Orcinus orca) in the Coastal Waters of British Columbia and Washington State.” In P. S. Hammond, S. A. Mizroch, and G. P. Donovan, eds., Individual Recognition of Cetaceans: Use of Photo-Identification and Other Techniques to Estimate Population Parameters, pp. 209-43. Report of the International Whaling Commission, Special Issue 12. Cambridge, UK: International Whaling Commission.

*Osborne, R. W. (1986) “A Behavioral Budget of Puget Sound Killer Whales.” In B. C. Kirkevold and J. S. Lockard, eds., Behavioral Biology of Killer Whales, pp. 211-49. New York: Alan R. Liss.

Reeves, R. R., and E. Mitchell (1988) “Distribution and Seasonality of Killer Whales in the Eastern Canadian Arctic.” In J. Sigurjonsson and S. Leatherwood, eds., North Atlantic Killer Whales, pp. 136–60. Rit Fiskideildar (Journal of the Marine Research Institute, Reykjavik), vol. 11. Reykjavik: Hafrannsok-nastofnunin.

*Rose, N.A. (1992) “The Social Dynamics of Male Killer Whales, Orcinus orca, in Johnstone Strait, British Columbia.” Ph.D. thesis, University of California–Santa Cruz.

*Saulitis, E. L. (1993) “The Behavior and Vocalizations of the ‘AT’ Group of Killer Whales (Orcinus orca) in Prince William Sound, Alaska.” Master’s thesis, University of Alaska.

*Utrecht, W. L. van (1960) “Notat om den hermafroditte spermhval/Note on the ‘Hermaphrodite Sperm Whale.’” Norsk Hvalfangst-Tidende 49:520.