List of animals displaying homosexual behavior

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

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.

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 ethical principles." 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]

  1. ^ Smith (February 7, 2004)
  2. ^ a b Bagemihl (1999)
  3. ^ a b News-medical.net (2006)
  4. ^ Bagemihl (1999) page 213
  5. ^ "Same-Sex Behavior Among Animals Isn't New. Science Is Finally Catching Up". National Wildlife Federation. Retrieved 2024-01-17.
  6. ^ "Same-Sex Behavior Among Animals Isn't New. Science Is Finally Catching Up". National Wildlife Federation. Retrieved 2024-01-17.
  7. ^ Harrold (1999)
  8. ^ Solimeo (2004)
  9. ^ Solimeo (2004b)
  10. ^ Bagemihl (1999) pages 122-166
  11. ^ Roughgarden (2004) pp.13-183
  12. ^ Vasey (1995) pages 173-204
  13. ^ Sommer & Vasey (2006)
  14. ^ Zimmer, Carl (3 October 2023). "Same-Sex Behavior Evolved in Many Mammals to Reduce Conflict, Study Suggests - But the researchers cautioned that the work could not shed much light on sexual orientation in humans. + comment". The New York Times. Archived from the original on 4 October 2023. Retrieved 4 October 2023.
  15. ^ Gómez, José M.; et al. (3 October 2023). "The evolution of same-sex sexual behaviour in mammals". Nature. 14 (5719): 5719. Bibcode:2023NatCo..14.5719G. doi:10.1038/s41467-023-41290-x. PMC 10547684. PMID 37788987.