For these animals, there is documented evidence of homosexual behavior of one or more of the following kinds: sex, courtship, affection, pair bonding, or parenting, as noted in researcher and author Bruce Bagemihl's 1999 book Biological Exuberance: Animal Homosexuality and Natural Diversity.
Roy and Silo, two Central Park Zoo male chinstrap penguins similar to those pictured, became internationally known when they successfully hatched and cared for an egg they were given.[1]Couple of male mallard ducks in a nature reserve in Germany
Bagemihl writes that the presence of same-sex sexual behavior was not "officially" observed on a large scale until the 1990s due to observer bias caused by social attitudes towards nonheterosexual people, making the homosexual theme taboo.[2][3] Bagemihl devotes three chapters, "Two Hundred Years at Looking at Homosexual Wildlife", "Explaining (Away) Animal Homosexuality" and "Not For Breeding Only" in his 1999 book Biological Exuberance to the "documentation of systematic prejudices" where he notes "the present ignorance of biology lies precisely in its single-minded attempt to find reproductive (or other) 'explanations' for homosexuality, transgender, and non-procreative and alternative heterosexualities."[4] Petter Bøckman, academic adviser for the Against Nature? exhibit, stated "[M]any researchers have described homosexuality as something altogether different from sex. They must realize that animals can have sex with who they will, when they will and without consideration to a researcher's ethicalprinciples." Homosexual behavior is found amongst social birds and mammals, particularly the sea mammals and the primates.[3][5] In 1986, it was even discovered amongst insects when butterfly scientist W.J. Tennent observed four male Mazarine blues competing for the attention of another male in Morocco.[6]
Sexual behavior takes many different forms, even within the same species and the motivations for and implications of their behaviors have yet to be fully understood. Bagemihl's research shows that homosexual behavior, not necessarily sex, has been documented in about five hundred species as of 1999, ranging from primates to gut worms.[2][7]Homosexuality in animals is seen as controversial by social conservatives because it asserts the naturalness of homosexuality in humans, while others counter that it has no implications and is nonsensical to equate natural animal behaviors to morality.[8][9] Sexual preference and motivation is always inferred from behavior. Thus homosexual behavior has been given a number of terms over the years. The correct usage of the term homosexual is that an animal exhibits homosexual behavior, however this article conforms to the usage by modern research,[10][11][12][13] applying the term homosexuality to all sexual behavior (copulation, genital stimulation, mating games and sexual display behavior) between animals of the same sex.
In October 2023, biologists reported studies of mammals (over 1,500 different species) that found same-sex behavior (not necessarily related to human orientation) may help improve social stability by reducing conflict within the groups studied.[14][15]
Homosexual behaviour is demonstrated by 120 known species of birds. [41] While an uptick in research on bird homosexuality – and animal homosexuality in general – has been coming out in recent years, it's common for some authors to labour in articulating the view any root cause or function of bird homosexuality is poorly understood.[42]
Hypotheses contrived in an attempt to explain the behaviour – homosexuality in birds – typically diverge from one another, further exacerbating an apparent perception in the concerned scientific communities knowledge's quest to realise bird homosexuality remains elusive as an objective. Some authors posit the behaviours are a result of any bird demonstrably homosexual being less inclined to rear young,[41] while other authors posit the timing of emergence from the egg is a factor.[43]
In 1977, The New York Times also reported on a colony of lesbian seagulls "off [the] coast of California."[44]
Arctic grayling (Thymallus arcticus) leaping for a fly fisherman's bait. Research going back to the 1950s has shown both male and female graylings exhibit homosexual behavior.[54]
The all-female Whiptail lizard species Aspidoscelis neomexicanus (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males, A. inornatus (left) and A. tigris (right). Research has shown that simulated mating behavior increases fertility for Aspidoscelis neomexicanus. One female lies on top of another, playing the role of the male, the lizard that was on bottom has larger eggs, in most cases. The lizards switch off this role each mating season.[61]
Harrold, Max (February 16, 1999). "Creature Comforts". The Advocate. No.779. pp.61–62. Retrieved March 10, 2018. In his news book, Biological Exuberance: Animal Homosexuality and Natural Diversity ... author Bruce Bagemihl portrays an animal kingdom that embraces a whole spectrum of sexual orientations ... [and] paints a complex mosaic that resembles humanity ... At 751 pages and with photos and documentation of homosexual behaviour in more than 450 species of mammals, birds, repties, and insects, Biological Exuberance brings the dusty facts to light as Bagemihl deconstructs the all-heterosexual Noah's Ark we've been sold.
Liggett, Dave; Columbus Zoo and Aquarium staff. "African Forest: Bonobo". Columbus Zoo and Aquarium. Archived from the original on June 2, 2002. Retrieved November 14, 2011. ...frequent sex (including male-to-male and female-to-female) characterize bonobo society.
Roselli, Charles E., Kay Larkin, John A. Resko, John N. Stellflug and Fred Stormshak (2004). "The Volume of a Sexually Dimorphic Nucleus in the Ovine Medial Preoptic Area/Anterior Hypothalamus Varies with Sexual Partner Preference". Endocrinology, Department of Physiology and Pharmacology, Oregon Health & Science University (C.E.R., K.L., J.A.R.), Portland, Oregon; Department of Animal Sciences, Oregon State University (F.S.), Corvallis, Oregon; and Agricultural Research Service, United States Sheep Experiment Station (J.N.S.), Dubois, Idaho, Vol. 145, No. 2. Retrieved on 10 September 2007.
Schaller, G. B. (1972). The Serengeti Lion; University of Chicago Press.
Smith, Dinitia (7 February 2004). "Love That Dare Not Squeak Its Name"New York Times. Retrieved on 10 September 2007. Reprinted as "Central Park Zoo's Gay Penguins Ignite Debate", San Francisco Chronicle.
Sell RL, Wells JA, Wypij D (June 1995). "The prevalence of homosexual behavior and attraction in the United States, the United Kingdom and France: results of national population-based samples". Archives of Sexual Behavior. 24 (3): 235–48. doi:10.1007/BF01541598. PMID7611844. S2CID12929812.
Wellings, K., Field, J., Johnson, A., & Wadsworth, J. (1994). Sexual behavior in Britain: The national survey of sexual attitudes and lifestyles. London, UK: Penguin Books.[pageneeded]
Benz G (May 1, 1973). "Role of sex pheromone, and its insignificance for heterosexual and homosexual behaviour of larch bud moth". Experientia. 29 (5): 553–554. doi:10.1007/BF01926659. S2CID39282068.
Out magazineArchived 2017-09-16 at the Wayback Machine, By The Numbers sourced to the Journal of Evolutionary Biology; February 2009. Accessed 2009-01-17.
Kureck, I. M.; Neumann, A.; Foitzik, S. (2011). "Wingless ant males adjust mate-guarding behaviour to the competitive situation in the nest". Animal Behaviour. 82 (2): 339–346. doi:10.1016/j.anbehav.2011.05.008. S2CID53164955.
Lecomte, C.; Thibout, E.; Pierre, D.; Auger, J. (1998-04-01). "Transfer, Perception, and Activity of Male Pheromone of Acrolepiopsis assectella with Special Reference to Conspecific Male Sexual Inhibition". Journal of Chemical Ecology. 24 (4): 655–671. doi:10.1023/a:1022390102631. ISSN0098-0331. S2CID10001697.
Baker T (January 15, 1983). "Variations in male oriental fruit moth courtship patterns due to male competition". Experientia. 39 (1): 112–114. doi:10.1007/BF01960660. S2CID99995.
Palaniswamy P, Seabrook W, Ross R (July 15, 1979). "Precopulatory behavior of males and perception of a potential male pheromone in spruce budworm". Annals of the Entomological Society of America. 72 (4): 544–551. doi:10.1093/AESA/72.4.544. S2CID84678927.
Chaudhuri A, Sinha A (July 15, 1997). "A male-male pairing in the tropical tasar silkmoth, Antheraea mylitta (Saturniidae)". News of the Lepidopterists' Society. 39 (3): 39.
Schmieder-Wenzel C, Schruft G (January 12, 1990). "Courtship behaviour of the European Grape Berry Moth, Eupoecilia ambiguella Hb. (Lep., Tortricidae) in regard to pheromonal and tactile stimuli". Journal of Applied Entomology. 109 (1–5): 341–346. doi:10.1111/j.1439-0418.1990.tb00062.x. S2CID86384073.