Biological Exuberance: Animal Homosexuality and Natural Diversity

This is true, for example, in Mallard Ducks, Black-crowned Night Herons, Black-headed Gulls, Emus, and Jackdaws.

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Red Deer (based on table 2, Hall 1983:278).

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Byne, W. (1994) “The Biological Evidence Challenged,” p. 53, Scientific American 270(5):50—55.

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Northern jacana (del Hoyo, J., A. Elliott, and J. Sargatal, eds. [1996] Handbook of the Birds of the World, vol. 3, Hoatzin to Auks, p. 282 [Barcelona: Lynx Edicións]); arctic tern and other species (Weldon, P. J., and G. M. Burghardt [1984] “Deception Divergence and Sexual Selection,” Zeitschrift für Tierpsychologie 65:89—102, especially table 1).

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Mountain Zebra (Penzhorn 1984:119); Chaffinch (Marler 1956:69, 96—97, 119) (Marler misleadingly labels some cases of opposite-sex mimicry as “homosexual behavior” while noting explicitly that no same-sex mounting occurs in these contexts); Rufous-naped Tamarin (Moynihan 1970:48, 50); Black-crowned Night Heron (Noble and Wurm 1942:216); Kittiwake (Paludan 1955:16-17); Koala (Smith 1980:49). Two species in which opposite-sex mimicry does appear to be a component of at least some homosexual interactions are Buff-breasted Sandpipers and Ocher-bellied Flycatchers.

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Northern Elephant Seal (Le Boeuf 1974:173); Black-headed Gull (van Rhijn 1985:87, 100); Red Deer (Darling 1937:170); Common Garter Snake (Mason and Crews 1985:59). Researchers have also found that transvestite paketi (a fish species) have huge testes that are about five times larger than that of nontransvestite males and are thus able to fertilize more eggs (Ayling, T. [1982] Sea Fishes of New Zealand, p. 255 [Auckland: Collins]; Jones, G. P. [1980] “Growth and Reproduction in the Protogynous Hermaphrodite Pseudolabrus celidotus [Pisces: Labridae] in New Zealand,” Copeia 1980:660-75).

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Tasmanian Native Hen (Ridpath 1972:30); Rhesus Macaque (Akers and Conaway 1979:76). On a related point, male Laysan Albatrosses may be stimulated to mount birds of either sex when the latter happen to assume a posture that resembles a female’s invitation to mate (typically involving drooping and spread wings)—to the extent that if only a bird’s right wing is drooping, for example, males on the bird’s right side will attempt to mount while those on the left will not. However, this “triggering” effect can only be a partial explanation, since males do not generally try to mount females who are sitting on a nest, even though the posture and drooping wings of such birds greatly resemble the mating invitation. Researchers studying this species (e.g., Fisher 1971:45-46) have expressed puzzlement over the apparent failure of the triggering effect in this context, suggesting that perhaps the height of the incubating females (nests in this species are six to eight inches high) is an inhibiting factor. This is not consistent, however, with the fact that males sometimes mount even taller “stacks” of up to three other males that are simultaneously mounting one another. Similarly, scientists once observed a Red Deer stag mount another male whose posture, as it was beginning to undergo the effects of a tranquilizer, supposedly “resembled” a female’s (Lincoln et al. 1970:101; cf. Klingel [1990:578] for a similar observation concerning anesthetized Plains Zebra stallions). Consequently, they attributed the homosexual behavior to the “triggering” effect of the supposedly femalelike visual cues presented by the other animal. Aside from the fact that the resemblance between a female Red Deer ready to mate and a drugged male is questionable, same-sex mounting in this species occurs commonly in contexts that have nothing to do with opposite-sex “resemblance” (cf. Hall 1983, Guiness et al. 1971; the same holds for Zebras).

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