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{671} Notes to Part I
      When no specific references are noted for a particular species in part 1, the information and sources will be found in the profile itself in part 2. When a note is included for a profiled species (e.g., to provide more detailed information), the citation format includes the species name, author, year, and (in most cases) page numbers of the source, referring to the full references in the profile. References for species that are not profiled in part 2 are included directly in notes.

      Introduction

      1
Einstein, A. (1930) "What I Believe," Forum and Century 84(4):193-94.

      Chapter 1. The Birds and the Bees

      1
Haldane, J. B. S. (1928) Possible Worlds and Other Papers, p. 298 (New York: Harper & Brothers).

      2
Animal names that are capitalized refer to a species or group of closely related species that is profiled in part 2, or whose references are included in the appendix.

      3
Homosexuality among primates, for example, has been traced back to at least the Oligocene epoch, 24-37 million years ago (based on its distribution among contemporary primates; Vasey 1995:195). Some scientists place its original appearance even earlier in the evolutionary line leading to mammals, at around 200 million years ago (Baker and Bellis 1995:5), and it has probably existed for much longer among other animal groups. Vasey, P. L. (1995) "Homosexual Behavior in Primates: A Review of Evidence and Theory," International Journal of Primatology 16:173-204; Baker, R., and M. A. Bellis (1995) Human Sperm Competition: Copulation, Masturbation, and Infidelity (London: Chapman and Hall).

      4
See note 29, as well as part 2 and the appendix, for more detailed tabulations (including discussion of species not included in this tally).

      5
For further discussion of sexual orientation in animals, as well as comparisons between animal and human homosexuality, see chapter 2. Following Vasey ("Homosexual Behavior in Primates," p. 175), the term homosexual is used to designate primarily the form of behaviors without necessarily implying anything about their "function or context or the actors' ages and motivation." For further consideration of the terminology used to describe same-sex activity in animals, including discussion of alternative definitions of the term homosexual(ity) as it is applied to animals (and some of the controversies that have surrounded its use in the zoological literature), see chapter 3. For more on the "functions" and contexts of homosexual behavior, see chapters 4-5.

      6
Guianan Cock-of-the-Rock (Endler and Thery 1996); Anna's Hummingbird (Hamilton 1965); Buff-breasted Sandpiper (Myers 1989).

      7
For a general survey of play-fighting, see Aldis, O. (1975) Play Fighting. (New York: Academic Press).

      8
Spinner Dolphin (Norris et al. 1994:250).
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      9
Ingestion of semen by both males and females during masturbation in heterosexual contexts also occurs among Golden Monkeys (Clarke 1991:371).

      10
Supernormal clutches have also been reported for pairs of male Emus, probably because more than one female has laid in their nest. What might be termed "subnormal" clutches — i.e., nests containing fewer eggs than are usually found for heterosexual pairs — are reported for female pairs of Blue Tits. And "super-supernormal" clutches occasionally occur in heterosexual pairs of Roseate Terns: as a result of within-species parasitism and possibly also egg transfer (see chapter 5 for more on these phenomena), some nests contain more than double the number of eggs found even in supernormal clutches (as is also true for "dump" nests in many Ducks and Geese).

      11
For discussion, and refutation, of the idea that same-sex pairs form in species such as these solely for the purpose of raising offspring, see chapter 5. In some birds such as grouse (e.g., sharp-tailed grouse, prairie chickens, white-tailed ptarmigan) and ducks (e.g., eiders, buffleheads) broods from more than one female are combined or "amalgamated" but no same-sex coparenting occurs (one female, or a heterosexual pair, look after all the offspring); cf. Bergerud and Gratson 1988:545 (Grouse); Afton 1993 (Ducks); Eadie, J. McA., E. P. Kehoe, and T. D. Nudds (1988) "Pre-Hatch and Post-Hatch Brood Amalgamation in North American Anatidae: A Review of Hypotheses," Canadian Journal of Zoology 66:1709-21.

      12
Ring-billed Gull (Conover 1989:148).

      13
In some bird species in which same-sex pairs are unable to obtain fertile eggs on their own (or in which homosexual parenting has yet to be observed in the wild), parenting skills have been demonstrated by supplying homosexual pairs with "foster" eggs or young in captivity. Same-sex pairs of Flamingos, White Storks, Black-headed Gulls, Steller's Sea Eagles, Barn Owls, and Gentoo Penguins, for example, have all successfully hatched such eggs and/or raised foster chicks.

      14
Black Swan (Braithwaite 1981:140-42); for more details, see chapter 5 and part 2.

      15
Ring-billed Gull (Conover 1989:148); Western Gull (Hayward and Fry 1993:17-18); see chapter 2 for further discussion of same-sex pairs being limited to nonoptimal territories. Several other studies point to the possibility of more "attentive" parenting by female homosexual pairs. Researchers have found that female Ring-billed Gulls in same-sex pairs, for example, may have higher levels of progesterone — a female hormone associated with nest-building and incubation behavior — than females in heterosexual pairs (Kovacs and Ryder 1985); see chapter 4 for more on the hormonal profiles of animals involved in same-sex activity. In a related set of observations, some investigators have documented more "intense" nesting behavior in female homosexual pairs than heterosexual pairs in some captive studies. Allen and Erickson (1982:346, 350), for instance, found that female pairs of Ring Doves are more persistent incubators than heterosexual pairs, being less likely to abandon their nests and terminate incubation when they have infertile eggs than are heterosexual pairs. Brockway (1967:76) found that female Budgerigars in homosexual pairs begin continuous occupation of their nests significantly sooner than females in heterosexual pairs. However, because female pairs begin noncontinuous occupation of their nests significantly later than heterosexual pairs in this species, the overall amount of their nesting activity and the timing of their egg-laying essentially evens out.

      16
See chapter 5 for further discussion of homosexual activity in communal groups and the often complex relationship between "helpers" and same-sex activity.

      17
In many species, young may also be raised in heterosexual trios, i.e., family units with three parents in which only opposite-sex bonding is present between the adults. See chapter 5 for some examples.

      18
For discussion of single parenting in animals where two (heterosexual) parents usually raise the young, as well as examples of other heterosexual parenting arrangements that deviate from the species-typical pattern, see chapter 5.

      19
For additional discussion of male bias in biological studies, see chapters 3 and 5.

      20
Rhesus Macaque (Altmann 1962:383; Lindburg 1971:69); Hamadryas Baboon (Abegglen 1984:63); Gelada Baboon (Bernstein 1970:94); Tasmanian Native Hen (Ridpath 1972:30); Gray-headed Flying Fox (Nelson 1965:546).

      21
Pukeko (Jamieson and Craig 1987a:1251 ); Bonobo (Thompson-Handler et al. 1984:349; Kano 1992:187; Kitamura 1989:55-57); Stumptail Macaque (Chevalier-Skolnikoff 1974:101, 110); Red Deer (Hall 1983:278); Red-necked Wallaby (LaFollette 1971:96); Northern Quoll (Dempster 1995:29).

      22
Pig-tailed Macaque (Oi 1990a:350-51): Galah (Rogers and McCulloch 1981); Pronghorn (Kitchen 1974:44).

      23
Gorilla (Fischer and Nadler 1978:660-61; Yamagiwa 1987a:12, 1987b:37).

      24
Pukeko (Jamieson and Craig 1987a:1251-52); Flamingo (C. E. King, personal communication). In Lesser Flamingos, however, the reverse appears to be true: males but not females achieve cloacal contact during their homosexual mounts (Alraun and Hewston 1997:176).

      25
Japanese Macaque (Hanby 1974:838-40; Wolfe 1984:149; Fedigan 1982:143).

      26
For further discussion of comparisons between animal and human homosexuality, see chapter 2.

      27
These formulas are also used to estimate the number of bisexual/heterosexual trios in a population; see Conover and Aylor 1985:127 (Ring-billed Gull).

      28
Kob (Buechner and Schloeth 1965); Long-tailed Hermit (Stiles and Wolf 1979). Likewise, up to 30 homosexual pairs of Herring Gulls have been counted in some locations — a relatively high number of same-sex associations to be present at one time — but in colonies that number more than 10,000 pairs, this amounts to less than I percent of the total number of pairs (Shugart 1980:426-27).
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      29
Same-sex courtship, sexual, pair-bonding, and /or parenting behaviors have been documented in the scientific literature in at least 167 species of mammals, 132 birds, 32 reptiles and amphibians 15 fishes, and 125 insects and other invertebrates, for a total of 471 species (see part 2 and appendix for a complete list). These figures do not include domesticated animals (at least another 19 species; see the appendix), nor species in which only sexually immature animals/juveniles engage in homosexual activities (for a survey of the latter in mammals, see Dagg 1984). For a number of reasons, this tally is likely to be an underestimate (especially for species other than mammals and birds, which are not as thoroughly covered): see chapter 3 for further discussion. It should also be pointed out that species totals may differ depending on the classificatory schema used; in some taxonomies, for example, animals that in this book are lumped together as subspecies are considered separate species (e.g., the various subspecies of Savanna Baboons, Flamingos, or Wapiti/Red Deer). This roster also excludes a wide variety of other cases in which the evidence for homosexual activities is not definitive, such as:
      1. species in which homosexual activity is suspected (and sometimes included in comprehensive surveys of homosexual behavior, such as Dagg 1984) but in which the sex of participants has not yet been coin-firmed (e.g., one-horned rhinoceros [Laurie 1982:323], yellow-bellied marmot [Armitage 1962:327], South African cliff swallow [Earle 1985:46], band-tailed barbfhroat hummingbird [Harms and Ahumada 1992], calliope hummingbird [Armstrong 1988], ringed Parakeet [Hardy 1964]).
      2. bird species in which supernormal clutches have been documented without any direct evidence of same-sex pairs (e.g., numerous gulls and other bird species; see note 70, chapter 4).
      3. same-sex trios or joint parenting arrangements with little or no conclusive evidence of courtship, sex, or pair-bonding between the like-sexed coparenis (e.g., bobolink [Bollinger et al. 1986], various ducks. grouse [cf. note 11, this chapter] ).
      4. bird species in which males associate in "pairs" or form "partnerships" with other males for joint displays during heterosexual courtships, but in which no overt courtship or sexual behavior occers between such partners or other same-sex individuals (e.g., several manakins of the genera Chiroxiphia, Pipra, Machaeropterus, and Masius — note however that males in these species often court "female-plumaged. birds, the sex of most of which has not been determined, while in two other species, some of these individuals have been determined to be males; wild turkey; king bird of paradise and possibly other birds of paradise. For further references, see McDonald 1989: (007 and Trainer and McDonald 1993:779).
      5. species in which the only form of documented "same-sex" activity involves individuals mounting het-crosexual copulating pairs, such that the mounting activity is not necessarily limited to like-sexed individuals or the same-sex motivation/orientation is not clear (e.g., camel and Dagg 1981:92], Buller's albatross [Warham 1967:129]).
      6. species in which the only same-sex activity is mounting that appears to be exclusively aggressive in character with no sexual component (e.g., collared lemming, degu, ground squirrel; of. Dagg 1984 and sources cited therein; see also chapter 3 for further discussion of aggressive or "dominance" mounting and the difficulty of distinguishing this from sexual mounting); and species in which the only same-sex activities are "affectionate" behaviors or "platonic" companionships unaccompanied by either signs of sexual arousal or overt courtship or sexual behaviors.
      7. other inconclusive cases, such as species reported in secondary sources as exhibiting homosexuality but whose original sources do not definitively document same-sex activity (e.g., avocets, reported in Terres [1980:813], with no mention of source, as engaging in homosexual mounting; Makkink [1936] and Hamilton [1975] — the most comprehensive primary field studies of this species and the most likely sources for this information — describe ritual mountings and masturbation "eruptive copulations"] but no homosexual mounting).
      Armitage, K. B. (1962) "Social Behavior of a Colony of the Yellow-bellied Marmut (Marmota flaviventris)." Animal Behavior 10:319-31; Armstrong, D. P. (1988) "Persistent Attempts by a Male Calliope Hummingbird, Stellula calliope, to Copulate with Newly Fledged Conspecifics," Canadian Field-Naturalist 102:259-60; Bollinger, E. K., T. A. Gavin, C. J. Hibbard, and J. T. Wootton (1986) "Two Male Bobolinks Feed Young at the Same Nest," Wilson Bulletin 98:154-56; Dagg, A. I. (1984) "Homosexual Behavior and Female-Wale Mounting in Mammals — a First Survey," Mammal Review 14:155-85; Earle, R. A. (1985) "A Description of the Social, Aggressive, and Maintenance Behavior of the South African Cliff Swallow Hirundo spilodera (Aves: Hirundinidae)," Navorsinge van die nasionale Museum, Bloemfontein 5:37-50; Gauthier-Pilters, H., and A. I. Dagg (1981) The Camel: Its Evolution, Ecology, Behavior, and Relationship to Man (Chicago: University of Chicago Press); Hardy, J.W. (1964) "Ringed Parakeets Nesting in Los Angeles, California," Condor 65:445-47; Harms, K. E., and J.A. Ahumada (1992) "Observations of an Adult Hummingbird Provisioning an Incubating Adult," Wilson Bulletin 104:369-70; Laurie, A. ( 1982) "Behavioral Ecology of the Greater One-horned Rhinoceros (Rhinoceros unicornis)," Journal of Zoology, London 196:307-41; Makkink, G. F. (1936) "An Attempt at an Ethogram of the European Avocet (Recurvirostra avosetta L.), With Ethological and Psychological Remarks," Ardea 25:1-63; McDonald, D. B. (1989) "Correlates of Male Mating Success in a Lekking Bird with Male-Male Cooperation," Animal Behavior 37:1007-22; Terres, J. K. (1980) The Audubon Society Encyclopedia of North American Birds (New York: Alfred A. Knopf); Trainer, J. M., and D. B. McDonald (1993) "Vocal Repertoire of the Long-tailed Manakin and Its Relation to Male-Male Cooperation," Condor 95:769-81; Warham, J. (1967) "Snares Island Birds," Notornis 14:122-39.
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      30
According to Wilson (1992), approximately 1,032,000 species of animals are currently known to science, although the number of actually occurring species is undoubtedly much higher — on the order of 10-100 million — and there are many complexities in estimating the total number of species. For further discussion, see Wilson, E. O. (1992) The Diversity of Life, pp. 131ff (Cambridge, Mass.: Belknap Press); Wilson, E. O. (1988) "The Current State of Biological Diversity," in E. O. Wilson, ed., BioDiversity, pp. 3-18. (Washington, D.C.: National Academy Press); May, R. M. (1988) "How Many Species Are There on Earth?" Science 241:1441-49.

      31
Le Boeuf and Mesnick 1991:155 (Elephant Seal); see also Wilson, E. O. (1975) Sociobiology: The New Synthesis (Cambridge and London: Belknap Press). This figure is borne out by the data on homosexuality: the average number of observation hours for scientific studies in which homosexual behavior has been observed is approximately 1,050 hours (based on data from 47 species in which the number of observation hours has been recorded).

      32
Marten, M., J. May, and R. Taylor (1982) Weird and Wonderful Wildlife, p. 7. (San Francisco: Chronicle Books). A somewhat more precise estimate of the number of species that have been adequately studied can be obtained for a subset of animals by using the Zoological Record (a comprehensive electronic database that indexes more than a million zoological source documents, including articles from over 6,000 journals worldwide, over the past 20 years). The Zoological Record for the period 1978-97 lists 825 mammal species in which at least some aspects of courtship, sexual, pair-bonding, mating-system, and/or parenting behaviors have been studied (the behavior categories in which homosexuality, if present, is likely to be found). Homosexual behavior has been documented in 133 of these species, or approximately 16 percent — comparable to the lower range obtained using the estimate of Marten et al. (The following subject headings/behavior categories indexed by Zoological Record were used in compiling this estimate: Courtship, Lek, Sexual Display, Precopulatory Behavior, Copulation, Mating, Pair Formation, Monogamy, Polygamy, Cooperative Breeding, Breeding Habits, Parental Care, Care of Young, Homosexuality).

      33
See chapter 4 for further discussion of these factors.

      34
For species that do not engage in "heterosexual" mating at all, e.g., parthenogenetic or hermaphrodite animals, see the next section.

      35
Clapham, P. J. (1996) "The Social and Reproductive Biology of Humpback Whales: An Ecological Perspective," p. 37, Mammal Review 26:27-49.

      36
Scott, P. E. (1994) "Lucifer Hummingbird (Calothorax lucifer)," in A. Poole and F. Gill, eds., The Birds of North America: Life Histories for the 21st Century, no. 134, p. 9. (Philadelphia: Academy of Natural Sciences; Washington, D.C.: American Ornithologists' Union); Dejong, M. J. (1996) "Northern Rough-winged Swallow (Stelgidopteryx serripennis)," in Poole and Gill, The Birds of North America, no. 234, p. 9; Kricher, J. C. (1995) "Black-and-white Warbler (Pheucticus melanocephalus)," in Poole and Gill, The Birds of North America, no. 158, p. 9; O'Brien, R. M. (1990) "Red-tailed Tropicbird (Phaethon rubricauda)", in S. Marchant and P. J. Higgins, eds., Handbook of Australian, New Zealand, and Antarctic Birds, vol. 1, part B, p. 940 (Melbourne: Oxford University Press); Johnsgard, P. A. (1983) Cranes of the World (Bloomington: Indiana University Press); Powers, D. R. (1996) "Magnificent Hummingbird (Eugenes fulgens)," in Poole and Gill, The Birds of North America, no. 221, p. 10; Hill, G. E. (1994) "Black-headed Grosbeak (Pheucticus melanocephalus)," in Poole and Gill, The Birds of North America, no. 143, p. 8; Victoria's Riflebird (Frith and Cooper 1996:103; Gilliard 1969:13); Cheetah (Caro 1994:42); Lepson, J. K., and L. A. Freed (1995) "Variation in Male Plumage and Behavior of the Hawaii Akepa," Auk 112:402-14; Spotted Hyena (Frank 1996:117); Agile Wallaby (Stirrat and Fuller 1997:75); Birds of Paradise (Davis and Beehler 1994:522); Nelson, S. K., and S. G. Sealy (1995) "Biology of the Marbled Murrelet: Inland and at Sea (Symposium Introduction)," Northwestern Naturalist 76:1-3; Orang-utan (Schurmann 1982; Schurmann and van Hoof 1986; Maple 1980); Rowe, S., and R. Empson (1996) "Observations on the Breeding Behavior of the Tanga'eo or Mangaia Kingfisher (Halcyon tuta rufi-collaris)," Notornis 43:43-48; Common Chimpanzee (Gagneux et al. 1997; Wrangham 1997); Harbor Seal (Perry and Amos 1998).

      37
Emu (Coddington and Cockburn 1995; Heinroth 1924); Black-rumped Flameback (Neelakantan 1962); Nilgiri Langur (Poirier 1970a,b); Harbor Seal (Johnson 1976:45); Northern Quoll (Dempster 1995); Gray-capped Social Weaver (Collias and Collias 1980); Walrus (Miller 1975; Fay et al. 1984); Acorn Woodpecker (Koenig and Stacey 1990:427); Australian Shelduck (Riggert 1977:20); Killer Whale (Jacobsen 1990:78; Rose 1992:1-2). See also Lutz and Voight 1994 for the first documentation of copulatory behavior — between two males — in two previously unknown species of deep-sea octopuses (a group in which heterosexual mating has yet to be observed in any species). Other animals in which same-sex activity has been documented and in which heterosexual activity has rarely been observed include Musk-oxen (Smith 1976:62), Red-necked Wallabies (Johnson 1989a:275), Vicunas (Koford 1957:182-84), Musk Ducks (Lowe 1966:285), and Ruffed Grouse (Johnsgard 1983:295). See chapter 4 for further discussion of the often insurmountable difficulties in attempting to observe and study sexual activity under field conditions.

      38
Ring-billed Gull (Conover and Aylor 1985). See chapter 4 for discussion of some of the pitfalls of equating homosexual pairings with supernormal clutches.

      39
Dragonflies (Dunkle 1991).

      40
Pukeko (Craig 1980); Pronghorn (Kitchen 1974). The behavior was probably classified as rare in Pronghorn because the amount of same-sex activity was not being compared to the amount of opposite-sex activity, but rather to the total amount of "dominance" behavior (which it was classified as), consisting primarily of nonsexual activities. For further discussion and critique of homosexuality interpreted as a "dominance" activity, see chapter 3.
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      41
Killer Whale (Rose 1992:116); Regent Bowerbird (Lenz 1994:266 [table 2]); White-handed Gibbon (Edwards and Todd 1991:233 [table 1]); Crab-eating Macaque (Thompson 1969:465).

      42
Giraffe (Pratt and Anderson 1985, 1982, 1979). In a study of another population of Giraffes, only three mounts between males were recorded, but only 400 hours of observation were involved (Dagg and Foster 1976:124).

      43
Mountain Sheep (Geist 1968:210-11 [tables 4, 6]); 1971:152 [table 30]).

      44
Gray Heron (Ramo 1993:116-17). In some species (e.g., Little Egrets, Little Blue Herons) quantitative information is only available for the proportion of promiscuous copulations that are homosexual (the higher figure). Where both proportions are available (e.g., Cattle Egrets, Gray Herons), an average of the two is taken when calculating cross-species comparisons of frequency (see below). Different frequencies can also be obtained depending on whether a distinction between copulatory and noncopulatory (or "ritualized") mounting is taken into account. (See chapter 3 for discussion of the — sometimes arbitrary — distinction between these two types of mounting.) In some cases, such as Pig-tailed and Crested Black Macaques, a sizable difference obtains. In Pigtails, 82 percent of mounting is same-sex if only noncopulatory mounts are considered (Oi 1990a:350-51 [table 4]), whereas 7-23 percent of all mounts are same-sex if "full" heterosexual copulations are included in the calculation (Bernstein 1967:226-7; Oi 1996:345). In Crested Blacks, roughly a third of noncopulatory mounts are between males, but overall this constitutes only about 8 percent of mounting activity when combined with copulatory (heterosexual) mounts (C. Reed, personal communication). In cases such as these, the latter (smaller) percentage is taken to be the overall rate of same-sex activity. For other species, however, the two rates are comparable. In Common Chimpanzees, for example, Nishida and Hosaka (1996:122, 129 [tables 9.7, 9.17a]) recorded 61 ritualized mounts between males compared to 123 male-female copulations (nonritualized), yielding a rate of 33 percent same-sex mountings. This is comparable to the exclusively noncopulatory figures of Bygott (1974; cited in Hanby 1974:845 [Japanese Macaque]), who found that 4 of 14 ritualized mounts (29 percent) occurred between males.

      45
Of course, these cross-species comparisons refer only to those animals in which homosexual behavior has been observed and in which the appropriate quantitative information is available. In many species same-sex behavior is more or less common than the maximum and minimum figures obtained from these measures, but it has not been quantified and therefore cannot be compared to these examples. For these calculations, if multiple frequency proportions were available for the same species — either because of population, seasonal, or behavioral differences (as discussed above) — these were averaged prior to being combined with the figures for other species. Proportions for courtship behavior are based on quantitative information from 21 species (avg = 23 percent same-sex activity), for sexual behavior from 77 species (avg = 26 percent), for pairing behavior from 45 species (avg = 14 percent), and for population percentages from 56 species (avg = 27 percent). For the purposes of comparison, tallies of observed homosexual and heterosexual behaviors in each species are assumed to be representative of actually occurring frequencies. The statistics for pairing and sexual behavior do not include the many species in which the only form of pair-bonding, coparenting, or observed sexual behavior is between same-sex individuals, i.e., in which 100 percent of pairs, coparents, or observed sexual interactions are homosexual (were these to be included, the proportions would be considerably, and perhaps unrepresentatively, higher). In five of these cases, however — Northern Elephant Seals, Cheetahs, Grizzly Bears, Lesser Scaup Ducks, and Greater Rheas — the proportion of all families or nests that are tended by same-sex pairs or trios (as opposed to single individuals) is substituted for the proportion of same-sex pairs. For population calculations, figures represent only the sex or activity that has been quantified (e.g., for species in which only females form same-sex pairs, or in which only female pairs have been tallied, only the proportion of females in such pairs is included). Moreover, for many bird species-especially those in which only a small fraction of individuals participate in same-sex activity — population percentages are not available. However, in species with same-sex pairing, the proportion of homosexual pairs is roughly comparable to the proportion of individuals engaging in same-sex activity (the two differ, of course, if there are sizable numbers of nonbreeding birds that do not form pairs with either sex). In order not to bias the sample toward species with relatively high population percentages, therefore, pairing proportions for wild-bird populations have been substituted. In species where no other population data are available, these figures are taken as a rough estimate of the proportion of individuals involved in same-sex activity.

      46
The term transgender, when it is applied to people, has two uses: as a cover term that refers to a wide variety of gender-crossing or gender-mixing phenomena, including transsexuality (with various degrees of hormonal and/or surgical transformation), transvestism (including cross-dressers, drag queens and kings, and female and male impersonators), intersexuality (including various forms of hermaphroditism), and even extremes of butch-femme presentation. It is also used as a designation for a specific form of gender mixing in which an individual lives full-time in the gender opposite to his or her anatomy (e.g., a man who passes for a woman without undergoing the full physical transitioning of a transsexual). For more discussion and exemplification see Feinberg, L. (1996) Transgender Warriors: Making History from Joan of Arc to RuPaul (Boston: Beacon Press).

      47
Foltz, D. W., H. Ochman, J. S. Jones, S. M. Evangelisti, and R. K. Selander (1982) "Genetic Population Structure and Breeding Systems in Arionid Slugs (Mollusca: Pulmonata)," Biological Journal of the Linnean Society 17:225-41.

      48
Of course, the term transvestism, when applied to people, refers primarily the wearing clothing of the opposite sex (and all of the attendant social and cultural repercussions). In its zoological usage, however, it simply refers to physical or behavioral attributes that are typical of the opposite sex in that species. For scientific use of this term, see the references in the notes for this section, as well as Weinrich, J. D. (1980) "Homosexual Behavior in Animals: (A New Review of Observations from the Wild, and Their Relationship to Human Sexuality," in R. Forleo and W. Pasini, eds., Medical Sexology: The Third International Congress, pp. 288-95. (Littleton, Mass.: PSG Publishing).
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      49
Owen, D. F. (1988) "Mimicry and Transvestism in Papilio phorcas (Lepidoptera: Papilionidae)," Journal of the Entomological Society of Southern Africa 51:294-96; Weldon, P. J., and G. M. Burghardt (1984) "Deception Divergence and Sexual Selection," Zeitschrift fur Tierpsychologie 65:89-102.

      50
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.

      51
Estes, R. D. (1991) "The Significance of Horns and Other Male Secondary Sexual Characters in Female Bovids," Applied Animal Behavior Science 29:403-51; Guthrie, R. D., and R. G. Petocz (1970) "Weapon Au-tomimicry Among Mammals," American Naturalist 104:585-88.

      52
Kirwan, G. M. (1996) "Rostratulidae (Painted-Snipes)," p. 297, in J. del Hoyo, A. Elliott, and J. Sargatal, eds., Handbook of the Birds of the World, vol. 3, Hoatzin to Auks, pp. 292-301 (Barcelona: Lynx Edicions). Examples such as these are often termed sex-role reversal by biologists.

      53
See the discussion of homosexual gender roles and interpretations of homosexuality as "pseudoheterosexuality" in chapter 4.

      54
Bighorn Sheep (Berger 1985). See also chapter 2 for further discussion of human and animal comparisons.

      55
Policansky, D. (1982) "Sex Change in Plants and Animals," Annual Review of Ecology and Systematics 13:471-95; Forsyth, A. (1986) A Natural History of Sex: The Ecology and Evolution of Mating Behavior, chapter 13. (New York: Scribner's).

      56
For surveys of transsexuality in fishes, see Potts, G. W., and R. J. Wootton, eds., (1984) Fish Reproduction: Strategies and Tactics (London: Academic Press); Warner, R. R. (1978) "The Evolution of Hermaphroditism and Unisexuality in Aquatic and Terrestrial Vertebrates," in E. S. Reese and F. J. Lighter, eds., Contrasts in Behavior: Adaptations in the Aquatic and Terrestrial Environments, pp. 77-101 (New York: Wiley); Warner, R. R. (1975) "The Adaptive Significance of Sequential Hermaphroditism in Animals," American Naturalist 109:61-82; Warner, R. R. (1984) "Mating Behavior and Hermaphroditism in Coral Reef Fishes," American Scientist 72:128-36; Policansky, "Sex Change"; Armstrong, C. N. (1964) Intersexuality in Vertebrates Including Man (London: Academic); Smith, C. L. (1975) "The Evolution of Hermaphroditism in Fishes," in R. Reinboth, ed., Intersexuality in the Animal Kingdom, pp. 295-310 (New York: Springer-Verlag); Smith, C. L. (1967) "Contribution to a Theory of Hermaphroditism," Journal of Theoretical Biology 17:76-90.

      57
Robertson, D. R., and R. R. Warner (1978) "Sexual Patterns in the Labroid Fishes of the Western Caribbean, II: The Parrotfishes (Scaridae)," Smithsonian Contributions to Zoology 255:1-26; Warner, R.R., and I. F. Downs (1977) "Comparative Life Histories: Growth versus Reproduction in Normal Males and Sex-changing Hermaphrodites in the Striped Parrotfish, Scarus croicensis," Proceedings of the Third International Symposium on Coral Reefs 1(Biology):275-82; Thresher, R. E. (1984) Reproduction in Reef Fishes (Neptune City, N.J.: T.F.H. Publications).

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Paketi: Jones, G. P. (1980) "Growth and Reproduction in the Protogynous Hermaphrodite Pseudolabrus celidotus (Pisces: Labridae) in New Zealand," Copeia 1980:660-75; Ayling, T. (1982) Sea Fishes of New Zealand, p. 255 (Auckland: Collins). Humbug damselfish: Coates, D. (1982) "Some Observations on the Sexuality of Humbug Damselfish, Dascyllus aruanus (Pisces, Pomacentridae) in the Field," Zeitschrift fur Tierpsychologie 59:7-18. Red Sea anemonefish: Fricke, H. W. (1979) "Mating System, Resource Defence, and Sex Change in the Anemonefish Amphiprion akallopisos," Zeitschrift fur Tierpsychologie 50:313-26. Lantern bass and others: Petersen, C. W., and E. A. Fischer (1986) "Mating System of the Hermaphroditic Coral-reef Fish, Serranus baldwini," Behavioral Ecology and Sociobiology 19:171-78; Nakashima, Y., K. Karino, T. Kuwamura, and Y. Sakai (1997) "A Protogynous Wrasse May Have a Functionally Simultaneous Hermaphrodite Phase," in M. Taborsky and B. Taborsky, eds., Contributions to the XXV International Ethological Conference, p. 214, Advances in Ethology no. 32 (Berlin: Blackwell Wissenschafrs-Verlag). Coral goby: Kuwamura, T., Y. Nakshima, and Y. Yogo (1994) "Sex Change in Either Direction by Growth-Rate Advantage in the Monogamous Coral Goby, Paragobiodon echinocephalus," Behavioral Ecology 5:434-38; Nakashima, Y., T. Kuwamura, and Y. Yogo (1995) "Why Be a Both-ways Sex Changer?" Ethology 101:301-7.
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