Biological Exuberance: Animal Homosexuality and Natural Diversity

mothers are occupied during the mating season, and orphaned calves are commonly adopted by other mothers or nonbreeding females. Occasionally, females even try to steal or “kidnap” calves from other females. Unfortunately, the lives of a calf and its mother are often endangered by male violence. Calves are sometimes gored by a male’s tusks, while mass tramplings may occur on haul-out sites—often triggered by belligerent Walrus bulls roaming through groups of females and their young. In some locations, such stampedes occur regularly, littering the beach with hundreds and even thousands of carcasses each year. Nearly a quarter of all fatalities are calves less than six months old, while 15 percent are aborted fetuses.

Sources

*asterisked references discuss homosexuality/transgender

Born, E.W., and L.O.Knutson (1997) “Haul-out and Diving Activity of Male Atlantic Walruses (Odobenus rosmarus rosmarus) in NE Greenland.” Journal of Zoology, London 243:381-96.

Dittrich, L. (1987) “Observations on Keeping the Pacific Walrus Odobenus rosmarus divergens at Hanover Zoo.” International Zoo Yearbook 26:163-70.

Eley, T. J., Jr. (1978) “A Possible Case of Adoption in the Pacific Walrus.” Murrelet 59:77-78.

Fay, F. H. (1982) Ecology and Biology of the Pacific Walrus, Odobenus rosmarus divergens Illiger. North American Fauna, no. 74. Washington, D.C.: U.S. Department of the Interior, Fish and Wildlife Service.

———(1960) “Structure and Function of the Pharyngeal Pouches of the Walrus (Odobenus rosmarus L.).” Mammalia 24:361-71.

*Fay, F. H., G. C. Ray, and A. A. Kibal’chich (1984) “Time and Location of Mating and Associated Behavior of the Pacific Walrus, Odobenus rosmarus divergens Illiger.” In F. H. Fay and G. A. Fedoseev, eds., Soviet-American Cooperative Research on Marine Mammals, vol. 1: Pinnipeds, pp. 89-99. NOAA Technical Report NMFS 12. Washington, D.C.: U.S. Department of Commerce.

Fay, F. H., and B. P. Kelly (1980) “Mass Natural Mortality of Walruses (Odobenus rosmarus) at St. Lawrence Island, Bering Sea, Autumn 1978.” Arctic 33:226-45.

*Mathews, R. (1983) “The Summer-Long Bachelor Party on Round Island.” Smithsonian 14:68-75.

Miller, E. H., (1985) “Airborne Acoustic Communication in the Walrus Odobenus rosmarus.” National Geographic Research 1:124-45.

*———(1976) “Walrus Ethology. II. Herd Structure and Activity Budgets of Summering Males.” Canadian Journal of Zoology 54:704-15.

*———(1975) “Walrus Ethology. I. The Social Role of Tusks and Applications of Multidimensional Scaling.” Canadian Journal of Zoology 53:590-613.

*Miller, E. H., and D. J. Boness (1983) “Summer Behavior of Atlantic Walruses Odobenus rosmarus rosmarus (L.) at Coats Island, N.W.T. (Canada).” Zeitschrift fur Saugetierkunde 48:298-313.

Nowicki, S. N., I. Stirling, and B. Sjare (1997) “Duration of Stereotyped Underwater Vocal Displays by Male Atlantic Walruses in Relation to Aerobic Dive Limit.” Marine Mammal Science 13:566- 75.

Ray, G. C., and W. A. Watkins (1975) “Social Function of Underwater Sounds in the Walrus Odobenus rosmarus.” Rapports et Proces-Verbaux des Reunions, Conseil International pour l’Exploration de la Mer 169:524-26.

*Salter, R. E. (1979) “Observations on Social Behavior of Atlantic Walruses (Odobenus rosmarus [L.]) During Terrestrial Haul-Out.” Canadian Journal of Zoology 58:461-63.

Schevill, W. E., W. A. Watkins, and C. Ray (1966) “Analysis of Underwater Odobenus Calls with Remarks on the Development and Function of the Pharyngeal Pouches.” Zoologica 51:103-6.

*Sjare, B., and I. Stirling (1996) “The Breeding Behavior of Atlantic Walruses, Odobenus rosmarus rosmarus, in the Canadian High Arctic.” Canadian Journal of Zoology 74:897-911.

Stirling, I., W. Calvert, and C. Spencer (1987) “Evidence of Stereotyped Underwater Vocalizations of Male Atlantic Walruses (Odobenus rosmarus rosmarus).” Canadian Journal of Zoology 65:2311-21.

IDENTIFICATION: A large (8-14 foot), streamlined, seal-like animal with a rounded tail, foreflippers but no hind legs, and a thick, hairless skin. DISTRIBUTION: Coastal waters and rivers of southeastern United States, the Caribbean, and northeastern Brazil; vulnerable. HABITAT: Shallow tropical and subtropical waters with abundant aquatic plants. STUDY AREAS: Crystal and Homosassa Rivers, Florida; subspecies T.m. latirostris, the Florida Manatee.

Social Organization

West Indian Manatees are generally solitary and only moderately social; however, they may congregate in loose herds of two to six animals. Some herds are cosexual, while others are “bachelor” groups of younger males.

Description

Behavioral Expression: Male West Indian Manatees of all ages regularly engage in intense homosexual activities. In a typical encounter, two males embrace, rub their genital openings against each other, and then unsheathe or erect their penises and rub them together, often to ejaculation. During a homosexual mating, the two males often tumble to the bottom, thrusting against each other and wallowing in the mud as they clasp each other tightly. A wide variety of positions are used, including embracing in head-to-tail and sideways positions, often with interlocking penises or flipper-penis contact. All of these are distinct from the position used for heterosexual copulation, in which the male typically swims underneath the female on his back and mates with her upside down. Lasting for up to two minutes, homosexual copulations are generally four to eight times longer than heterosexual ones. Before they engage in sexual activity, males often “kiss” each other by touching their muzzles at the surface of the water. In addition, several other types of affectionate and tactile activities are a part of homosexual interactions, including mouthing and caressing of each other’s body, nibbling or nuzzling of the genital region, and riding by one male on the back of the other (a behavior also seen in heterosexual interactions). Sometimes a male emits vocalizations indicating his pleasure during homosexual activity, variously described as high-pitched squeaks, chirp-squeaks, or snort-chirps. If, however, he is not interested in participating, he may emit a squealing sound, slapping his tail as he flees from the other male (just the way females do when trying to escape from unwanted advances of males).

Often several males participate at the same time in homosexual interactions: groups of up to four animals have been seen kissing, embracing each other in an interlocked “hug,” thrusting, and rubbing their penises against one another. These homosexual “orgies” can last for hours as new males arrive to join the group, subgroups form and re-form, and participants leave and return. Homosexual behavior is often part of a social activity known as CAVORTING, in which animals travel and splash about in groups, nuzzling, grabbing, chasing, rubbing, and rolling against one another. Cavorting groups can be mixed-sex or all-male.

Frequency: Homosexuality is common among West Indian Manatees. In addition, males spend on average about 11 percent of their time in cavorting groups.

Orientation: Most male Manatees are probably bisexual, since