Biological Exuberance: Animal Homosexuality and Natural Diversity

Australian Shelduck (Riggert 1977:60-61); Ring-billed Gull (Conover and Hunt 1984a); Mute Swan (Kear 1972:85-86); Mountain Sheep (Geist 1971:162); Bottlenose Dolphin (Tavolga 1966:729—30); Killer Whale (Rose 1992:112); White-handed Gibbon (Edwards and Todd 1991:234); West Indian Manatee (Hartman 1979:107-8); Hanuman Langur (Srivastava et al. 1991:508—9); Asiatic Elephant (Ramachandran 1984); Lion (Chavan 1981); Sage Grouse (Scott 1942:488).

35

For explicit rejection of (and evidence against) the shortage hypothesis by various zoologists studying animal homosexuality, see Gorilla (Harcourt et al. 1981:276); Japanese Macaque (Fedigan and Gouzoules 1978:494; Vasey 1996:550, 1998:17); Rhesus Macaque (Akers and Conaway 1979:77); Flamingo (King 1994:107); Common Gull (Riddiford 1995:112); Jackdaw (Roell 1978:103); Galah (Rogers and McCulloch 1981:90; Rowley 1990:59-60).

36

Orang-utan (Rijksen 1978:259); Japanese Macaque (Vasey 1996 and personal communication; Corradino 1990:360; Wolfe 1984); Stumptail Macaque (Chevalier-Skolikoff 1976:520); Rhesus Macaque (Akers and Conaway 1979:76–77); Common Gull (Riddiford 1995:112); Black-headed Gull (van Rhijn 1985:91–93); King Penguin (Murphy 1936:340—41); Galah (Rogers and McCulloch 1981:90; Rowley 1990:59–60).

37

Bottlenose Dolphin (Ostman 1991:310); Squirrel Monkey (Mendoza and Mason 1991:476–77; Travis and Holmes 1974:55, 63); Bonobo (Kano 1992:149; Savage-Rumbaugh and Wilkerson 1979:338); Stumptail Macaque (Chevalier-Skolikoff 1976:524); Savanna (Yellow) Baboon (Maxim and Buettner-Janusch 1963:176); West Indian Manatee (Hartman 1979:101, 106); Pukeko (Jamieson and Craig 1987a:1251); Common Murre (Birkhead et al. 1985:614); Sociable Weaver (Collias and Collias 1980b:248); Bonnet Macaque (Sugiyama 1971:252, 259—60); Japanese Macaque (Vasey 1996:543 and personal communication). Homosexual mounting rates can also be independent of the presence of animals of the opposite sex: in an all-female group of Pig-tailed Macaques, for example, the rate of same-sex mounting was virtually identical both before and after introduction of a male into the group (Giacoma and Messeri 1992:183 [table I]). The finding of a positive correlation between homosexual and heterosexual rates is paralleled by some data on humans in sex-segregated environments. Researchers found that married men in prisons who receive conjugal visits with their wives are actually more likely to have sex with other male prisoners than men without conjugal visits (Wooden, W. S., and J. Parker [1982] Men Behind Bars: Sexual Exploitation in Prison, pp. 55–56 [New York: Plenum]).

38

For species with skewed sex ratios but no homosexuality, see Welty, J. C., and L. Baptista (1988) The Life of Birds, 4th ed., p. 154 (New York: W. B. Saunders); Newton, I. (1986) The Sparrowhawk, pp. 37, 151 (Calton, England: T. and A. D. Poyser); Taborsky, B., and M. Taborsky (1991) “Social Organization of North Island Brown Kiwi: Long-Term Pairs and Three Types of Male Spacing Behavior,” Ethology 89:47-62. For verification of balanced sex ratios in populations exhibiting homosexuality, see Bonobo (Thompson-Handler et al. 1984:349); Bonnet Macaque (Simonds 1965); West Indian Manatee (Hartman 1979:139); Snow Goose (Quinn et al. 1989:184); California Gull (Conover et al. 1979); Pukeko (Craig 1980:594).

39

For sex ratios of various Seals and Sea Lions, see Fay 1982:256 (Walrus); for lunulated and salvin’s antbirds, see Willis, E. O. (1968) “Studies of the Behavior of Lunulated and Salvin’s Antbirds,” Condor 70:128—48; for other antbird species with a “surplus” of unmated males but no homosexual pairs, see Willis, E. O. (1969) “On the Behavior of Five Species of Rhegmatorhina, Ant-Following Antbirds of the Amazon Basin,” Wilson Bulletin 81:363–95.

40

Crab-eating Macaque (Poirier and Smith 1974); Pukeko (Craig 1980:594); Rhesus Macaque (Lindburg 1971:14, 69); Tree Swallow (Stutchbury and Robertson 1985, 1987b); Galah (Rogers and McCulloch 1981:90); Scarlet Ibis (Elbin and Lyles 1994:90–91); Flamingo (King 1994:104–5); Nilgiri Langur (Hohmann 1989:449); Little Egret (M. Fujioka, personal communication); Little Blue Heron (Werschkul 1982:382).

41

Black Stilt (Reed 1993:772); Humboldt Penguin (Scholten 1992:6 and personal communication); Savanna (Yellow) Baboon (Rowell 1967a:16, 22—23 [tables 2, 3]); Mallard Duck (Lebret 1961:108 [table I]).

42

Pig-tailed Macaque (Oi 1990a:340); Bottlenose Dolphin (Wells 1991:222); Cheetah (Eaton and Craig 1973:252); Koala (Smith 1980:184); Canada Goose (Collias and Jahn 1959:484); Flamingo (C. E. King, personal communication); Lesser Flamingo (Alraun and Hewston 1997:175–76).

43

Japanese Macaque (Chapais and Mignault 1991:172; Wolfe 1984:155); Giraffe (Dagg and Foster 1976:28, 124, 144); Greylag Goose (Huber and Martys 1993:160). Likewise, in Northern Fur Seal populations with up to 40 or more females for every male, a number of behavioral and other factors insure that nearly every female is still able to mate heterosexually (Gentry 1998:167, 192–93). For Macaques, some researchers have suggested that females resort to homosexuality when deprived of “novel” male partners rather than of males per se (i.e., when they “run out” of new partners or become overly familiar with them) (Wolfe 1984:155, 1986:274 [Japanese Macaque]; Huynen 1997 [Rhesus Macaque]). As Vasey (1996:550) points out, however, this explanation is flawed because the females they turn to are no more “novel” than the males are (and probably even less so, owing to the high levels of female bonding and familiarity in these species). In addition, some females continue to choose other females as partners even in populations that have novel males.

44

Gorilla (Robbins 1996; Fossey 1983, 1984; Harcourt et al. 1981); Hanuman Langur (Weber and Vogel 1970) Crested Black Macaque (Reed et al. 1997; Dixson 1977); Squirrel Monkey (DuMond 1968; Travis and Holmes 1974; Akers and Conaway 1979; Denniston 1980; Mendoza and Mason 1991); Walrus (Miller and Boness 1983; Sjare and Stirling 1996); Lion (Schaller 1972; Chavan 1981); Mallard Duck (Bossema and Roemers 1985; Schutz 1965:457– 59); Black-headed Gull (Kharitonov and Zubakin 1984); West Indian Manatee (Hartman 1971, 1979); Cheetah (Eaton and Craig 1973; Eaton 1974a). In some of these cases (e.g., Gorillas, Hanuman Langurs) homosexual activity among males is much more common in same-sex groups although it still occurs sporadically or “residually” in mixed groups; in other cases (e.g., Squirrel Monkeys, Crested Black Macaques) homosexual activity is equally if not more common in at least some mixed-sex groups.

45

Squirrel Monkey (Talmage-Riggs and Anschel 1973:68, 71); Long-eared Hedgehog (Poduschka 1981:81).

46

Silver Gull (Mills 1991:1523, 1526); Mallard Duck (Schutz 1965:442); Canada Goose (Collias and Jahn 1959:500); Jackdaw (Roell 1979:126, table 1); Lesser Scaup Duck (Bellrose 1976:344); Caribou (Bergerud 1974:432).

47

Flamingo (Wilkinson 1989:53-54; King 1994:105; C. E. King, personal communication); Laughing Gull (Hand 1981:138-39); Humboldt Penguin (Scholten 1992:5); Gentoo Penguin (Stevenson 1983:192); Pied Kingfisher (Moynihan 1990:19; Reyer 80:220); Peach-faced Lovebird (Fischdick et al 1984:314); Galah (Rogers and McCulloch 1981:90); Bicolored Antbird (Willis 1967:112).

48

Cattle Egret (Fujioka 1986b:421-22); emperor and other penguins (Williams, T. D. [1995] The Penguins: Spheniscidae, pp. 80, 160 [Oxford: Oxford University Press]); dipper (Wilson, J. D. [1996] “The Breeding Biology and Population History of the Dipper Cinclus cinclus on a Scottish River System,” Bird Study 43:108—18); Oystercatcher (Heg and van Treuren 1998); Australian noisy miner (Dow, D. D., and M. J. Whitmore [1990] “Noisy Miners: Variations on the Theme of Communality,” in P. B. Stacey and W. D. Koenig, eds., Cooperative Breeding in Birds: Long-Term Studies in Behavior, pp. 559--92 [Cambridge: Cambridge University Press]); spotted sandpiper (Oring, L. W., J. M. Reed, and S. J. Maxson [1994] “Copulation Patterns and Mate Guarding in the Sex-Role Reversed,