Biological Exuberance: Animal Homosexuality and Natural Diversity

In Western Gulls, the correlation between toxins and supernormal clutches is claimed to be supported by chronological evidence: larger clutches were supposedly not common prior to the widespread use of pesticides in the 1950s–1970s in southern California, while female pairs are claimed to occur at a “much lower” rate (Hayward and Fry 1993:19) or to have all but disappeared (Pierotti and Annett 1995:11) now that pesticide use has stopped. However, no comprehensive survey of the affected areas has in fact been conducted to assess the actual incidence of female pairs today (even if such a study were to find consistently low levels, this would still be significant, since it would demonstrate a “residual” component of same-sex activity that is independent of toxin effects and of a “shortage” of the opposite sex, as is true for many other species). Nor have detailed longitudinal or geographic studies been conducted to track the putative correlations during this entire five-to-six-decade period. In fact, records of supernormal clutches in Ring-billed Gulls go back much earlier, to the early 1900s (and in other species back to the late 1800s), while in some Terns their frequency has actually decreased since the 1950s (Conover 1984c), so the chronological question is far from resolved. At least one researcher who has addressed the temporal issue rejects the DDT (or other pollutant) connection for the majority of cases: Conover (1984c:254) conducted an extensive survey of the occurrence of supernormal clutches in 34 species, including comparing pre- and post-1950 rates, and concluded that their frequency is not higher since the 1940s for most Gull and Tern species. Finally, no studies have yet determined the incidence of homosexual pairing/supernormal clutches in other regions of the world that have the highest levels of contamination from DDT and related pollutants, such as the Baltic Sea, the Waddensee, the Irish Sea, the Gulf of St. Lawrence, and the northern Gulf of Mexico (Nisbet, I. C. T. [1994] “Effects of Pollution on Marine Birds,” p. 13, in D. N. Nettleship, J. Burger, and M. Gochfeld, eds. Seabirds on Islands: Threats, Case Studies, and Action Plans, pp. 8–25. [Cambridge: BirdLife International]).

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Hayward and Fry 1993:19; Luoma, J. R. (1995) “Havoc in the Hormones,” Audubon 97(4):60-67; Robson, B. (1997) “A Chemical Imbalance,” Nature Canada 26(1):29-33; see also Coulson 1983 (Caspian Tern). The equating of homosexuality with environmental and physiological “havoc” has also entered the more popular discourse, as in a recent public radio broadcast that referred to lesbian pairs in Gulls as evidence of hormonal imbalances caused by environmental contamination (“Gator Envy,” All Things Considered, National Public Radio, February 1, 1995). Some things not considered in this report were the broader context of same-sex pairing in other species and the intricacies of the specific cases. For more on the pathologizing of homosexuality, see the following section “Gross Abnormalities of Behavior.”

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See, for example, Aiken (1981) on Water Boatman Bugs. Even this case is somewhat less than definitive, however, since more than half of all mating attempts in this species are by males on other males.

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Guianan Cock-of-the-Rock (Trail 1985a:238, 240); Giraffe (Spinage 1968:130); Black-billed Magpie (Baeyens 1979:39–40); Mountain Sheep (Geist 1968:208). For examples of homosexual interactions that are explicitly labeled “mistakes” or “errors” (including, but not limited to, cases of sex misrecognition), see Asiatic Mouflon (Schaller and Mirza 1974:318-20); Common Murre (Birkhead et al. 1985:610-11); Oystercatcher (Makkink 1942:60); Laughing Gull (Hand 1981:139–40); Greater Rhea (Fernández and Reboreda 1995:323).

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