Bruce Bagemihl - Biological Exuberance

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Andersson, S., J. Ornborg, and M. Andersson (1998) “Ultraviolet Sexual Dimorphism and Assortative Mating in Blue Tits,” Proceedings of the Royal Society of London , Series B 265:445–50; Hunt, S., A. T. D. Bennett, I. C. Cuthill, and R. Griffiths (1998) “Blue Tits Are Ultraviolet Tits,” Proceedings of the Royal Society of London, Series B 265:451-55; Witte, K., and M. J. Ryan (1997) “Ultraviolet Ornamentation and Mate Choice in Bluethroats,” in M. Taborsky and B. Taborsky, eds., Contributions to the XXV International Ethological Conference, p. 201, Advances in Ethology no. 32 (Berlin: Blackwell Wissenschafts-Verlag); Roper, T. J. (1997) “How Birds Use Sight and Smell,” Journal of Zoology, London 243:211-13; Bennett, A. T. D., I. C. Cuthill, J. C. Partridge, and E. J. Maier (1996) “Ultraviolet Vision and Mate Choice in Zebra Finches,” Nature 380:433-35; Waldvogel, J. A. (1990) “The Bird’s Eye View,” American Scientist 78:342-53; Cabbage White Butterfly (Obara 1970 and personal communication; Obara, Y [1995] “The Mating Behavior of the Cabbage White Butterfly,” paper presented at the 24 thInternational Ethological Conference, Honolulu, Hawaii); Superb Lyrebird (Reilly 1988:45).

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Mountain Goat (Geist 1964:565); Musk-ox (Smith 1976:56); Cavies (Rood 1972:27, 54, 1970:443); Bighorn Sheep (Geist 1968:208); Common Murre (Birkhead et al. 1985:610-11); Flamingo (C. E. King, personal communication); Pronghorn (Kitchen 1974:44 [table 22]). In addition, some homosexual activity in Mountain Goats and Pronghorns also involves age-mates interacting with each other (adult males in Mountain Goats, younger males in Pronghorns). See also Wagner (1996) on Razorbills.

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Swallow-tailed Manakin (Foster 1987:555); Laughing Gull (Noble and Wurm 1943:205); Black-headed Gull (van Rhijn and Groothuis 1985:163). Conversely, homosexuality has sometimes been attributed to behavioral identity between males and females. In Ruffed Grouse, for example, the nonaggressive or “submissive” posture of a male is similar to the behavior of a female during courtship, and that males court both sexes is attributed to their inability to distinguish “female-acting” males from actual females (Allen 1934:185; see also the discussion of “pseudoheterosexuality” earlier in this chapter). Aside from the fact that males and females are very different visually from each other in this species and therefore “there is no excuse for a male not recognizing a female” (as Allen [1934:180-81] observes), in the related red grouse there is a parallel identity between male “submissive” and female courtship behavior, yet males do not court other males in this species (Watson, A., and D. Jenkins [1964] “Notes on the Behavior of the Red Grouse,” British Birds 57:157).

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Tree Swallow (Stutchbury and Robertson 1987a:719-20, 1987b:418). It is also unlikely that homosexual activity between adult males results from their mistaking one another for (adult) females. As Lombardo et al. (1994) point out, although the two sexes in this species look similar, the sex of at least one male involved in homosexual activity was nevertheless identifiable from his cloacal (genital) protuberance, lack of brood patch, and wing length. Most adult females are also visually distinct from males owing to the presence of a brown patch on the forehead (shorter wings also distinguish subadult females from subadult males) (Stutchbury and Robertson 1987c). In addition, same-sex copulations appear to be fairly uncommon in this species (Lombardo, personal communication)—certainly they are not nearly as frequent as one would expect if “mistakes” in sex recognition were prevalent.

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Black-headed Gull (van Rhijn 1985:87, 100).

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Hooded Warbler (Niven 1993:191) (cf. Lynch et al. [1985:718] for mean dimensions of other males). Niven (1993 and personal communication) suggests that it was also the female behavior patterns of this male that “triggered” the homosexual pairing, yet this bird’s behavior was actually a mixture of male and female patterns, involving, for example, incubation (female duties) as well as singing (male). Moreover, male Hooded Warblers are particularly attuned to differences in song pattern, using this information to recognize individual birds and then storing it in long-term memory for future use (Godard 1991). Because this male’s singing was highly distinctive, it is improbable that other males simply “disregarded” this aspect of his behavior or were “unaware” of his male status (especially given his physical characteristics). Furthermore, all “female” behaviors recorded in this individual occurred after the formation of the pair-bond—since pairs were not observed early in the breeding season, we do not in fact know whether this individual exhibited any (or only) “femalelike” patterns during courtship and pair-formation.

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Hooded Warbler: differential attacking of males (Stutchbury 1994:65-67); mating success of malelike females (as evidenced by the fact that nests are fairly equally distributed between dark and light females) (Stutchbury et al. 1994:389[fig.6]; Stutchbury and Howlett 1995:95); promiscuous mating attempts on hooded females (Stutchbury et al. 1994:388).

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Common Garter Snake (Mason 1993:261, 264; Mason et al. 1989:292; Mason and Crews 1985; Noble 1937:710–11); other species (Muma, K., and P. J. Weatherhead [1989] “Male Traits Expressed in Females: Direct or Indirect Sexual Selection?” Behavioral Ecology and Sociobiology 25:23-31; Potti, J. [1993] “A Male Trait Expressed in Female Pied Flycatchers Ficedula hypoleuca: The White Forehead Patch,” Animal Behavior 45:1245-47 [cf. also Sætre and Slagsvold 1992:295-96]; Tella, J.L., M. G. Forero, J.A. Donázar, and F. Hiraldo [1997] “Is the Expression of Male Traits in Female Lesser Kestrels Related to Sexual Selection?” Ethology 103:72-81; McDonald, D. B. [1993] “Delayed Plumage Maturation and Orderly Queues for Status: A Manakin Mannequin Experiment,” p. 38, Ethology 94:31-45). Experimental “disguising” of individuals to look like the opposite sex does not automatically induce “homosexual” behavior either. Female Chaffinches whose plumage has been painted to resemble male patterns, for example, are not courted by (nor do they form pair-bonds with) other females that “mistake” them for males (Marler 1955). Homosexual pairing does occur in this species, but between females that do not look like males. Likewise, yellowthroats (a bird species) are able to recognize the “true” sex of both males and females whose facial coloration has been manipulated to make them resemble the opposite sex. Similar results have been found for damselflies (Lewis, D. M. [1972] “Importance of Face-Mask in Sexual Recognition and Territorial Behavior in the Yellowthroat,” Jack-Pine Warbler 50:98-109; Gorb, S. N. [1997] “Directionality of Tandem Response by Males of a Damselfly, Coena-grion puella,” in M. Taborsky and B. Taborsky, eds., Contributions to the XXV International Ethological Conference, p. 138. Advances in Ethology no. 32 [Berlin: Blackwell Wissenschafts-Verlag]). In addition, in species such as lazuli buntings where juvenile males resemble adult females, experimental studies have demonstrated that adult males are in fact consistently able to distinguish the two sexes (Muehter, V. R., E. Greene, and L. Ratcliffe [1997] “Delayed Plumage Maturation in Lazuli Buntings: Tests of the Female Mimicry and Status Signalling Hypotheses,” Behavioral Ecology and Sociobiology 41:281–90).

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Tree Swallow (Lombardo et al. 1994:555–56; Venier et al. 1993; Venier and Robertson 1991); Black-crowned Night Heron (Noble et al. 1938:29); Regent Bowcrbird (Marshall 1954:114-16); Greenshank (Nethersole-Thompson and Nethersole-Thompson 1979:114; Nethersole-Thompson 1951:104). In Tree Swallows, it is also unlikely that males cooperate during homosexual copulations in order to “appease” the birds mounting them and thereby avoid attack or injury (as suggested by Lonrbsrdo et al. 1994:556). Aggressive attacks in this species are characterized by a number of distinctive behavioral elements on the part of both the attacker (e.g., threat displays, grappling, pecking) and the bird being attacked (e.g., appeasement displays, submissive and distress calling) (cf. Robertson et al. 1992:6, 8)—and homosexual mountings exhibit none of these hallmarks.