Bruce Bagemihl - Biological Exuberance

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And sometimes the correlation between the two end points is itself suspect. For example, it has been claimed that supernormal clutches are more common in Great Lakes populations of Herring Gulls than they are in New England, a fact that is attributed to greater levels of DDT poisoning in the Great Lakes (Conover 1984c:254) and/or the absence of available nesting sites in New England (Fry et al. 1987:40; see note 65 above). However, Nisbet and Drury (1984:88) show that the “higher rate” of supernormal clutches in the Great Lakes can be traced to only one particular colony site; in three other Great Lakes areas censused, the prevalence of supernormal clutches was no greater than in New England. Moreover, even if such clutches are more common in the Great Lakes area, the fact that they still occur in New England indicates that their presence cannot be due entirely to pollutant-related (or nest-site availability) factors.

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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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Redshank (Hale and Ashcroft 1982:471). Other species in which the occurrence of homosexuality is taken as the sole evidence of faulty sex recognition or “indiscriminate” mating or courtship include Cavies (Rood 1970:449), Little Brown Bats (Thomas et al. 1979:134), Shags (Snow 1963:93-94), Little Egrets (Fujioka 1988), Oystercatchers (Makkink 1942:67–68), Black-headed Gulls (van Rhijn 1985:87, 93), Superb Lyrebirds (Lill 1979a:496), and King Penguins (Murphy 1936:340). It should also be pointed out that the claim of “indiscriminate” sexual activity is often quite exaggerated: it is not uncommon for the mere existence of same-sex activity to be interpreted as evidence that the sex of the partner is immaterial, even when the animals show clear partner preferences, sometimes even favoring homosexual activity. For example, Trail and Koutnik (1986:210–11) claim that yearling Guianan Cock-of-the-Rock will mount any bird that sits still long enough; in fact, only one attempted heterosexual mount by a yearling was recorded during their study, compared to hundreds of homosexual mounts, and certain adult males were clearly mounted more often than others (ibid., 211–12, 215).

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Yellow-eyed penguin (Richdale, L. E. [1951] Sexual Behavior in Penguins, p. 73 [Lawrence, Kans.: University of Kansas Press]); Silvery Grebe (Nuechterlein and Storer 1989:344); Red-faced Lovebird (Dilger 1960:667).

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For species with adult-female/younger-male resemblances, see Rohwer, S., S. D. Fretwell, and D. M. Niles (1980) “Delayed Maturation in Passerine Plumages and the Deceptive Acquistion of Resources,” American Naturalist 115:400-437; for species with adult-female/adult-male resemblances, see Burley, N. (1981) “The Evolution of Sexual Indistinguishability,” in R. D. Alexander and D. W. Tinkle, eds., Natural Selection and Social Behavior, pp. 121-37 (New York: Chiron Press). A caveat about these cases is that the absence of homosexuality in a species is not necessarily a reliable form of evidence, since (as discussed in chapters 1-3) homosexual behavior is often hard to observe, easy to overlook, or deliberately ignored in the field.

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Blackbuck (Dubost and Feer 1981:74-75); Guianan Cock-of-the-Rock (Trail and Koutnik 1986:199; Trail 1983); Swallow-tailed Manakin (Foster 1987:549; Sick 1967:17; 1959:286); Blue-backed Manakin (Snow 1963:172); Raggiana’s Bird of Paradise, Victoria’s Riflebird (Gilliard 1969:113, 223); Regent Bowerbird (Gilliard 1969:337); Superb Lyrebird (Smith 1982 and personal communication).

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Mountain Goat (Chadwick 1983:14, 189–91); Bishop Birds (Craig and Manson 1981:13); Galah (Rogers and McCulloch 1981:81; Rowley 1990:4); Humboldt Penguin (Scholten 1987:200); King Penguin (Stonehouse 1960:11); Superb Lyrebird (Smith 1982 and personal communication); Ocher-bellied Flycatcher (Westcott and Smith 1994:678, 681; Snow and Snow 1979:286); Tree Swallow (Stutchbury and Robertson 1987c); Anna’s Hummingbird (Ortiz-Crespo 1972; Wells et al. 1996).