List of animals displaying homosexual behavior

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Two New York Central Park Zoo's male chinstrap penguins, similar to those pictured, became internationally known when they coupled and later were given an egg that needed hatching and care, which they successfully did.^[1]

This list includes animals (birds, mammals, insects, fish, etc.) for which there is documented evidence of homosexual or transgender 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 possible observer bias caused by social attitudes towards LGBT 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 states

"[M]any researchers have described homosexuality as something altogether different from sex. They must realise that animals can have sex with who they will, when they will and without consideration to a researcher's ethical principles".

Homosexual behavior is widespread amongst social birds and mammals, particularly the sea mammals and the primates.^[3]

"No species has been found in which homosexual behaviour has not been shown to exist, with the exception of species that never have sex at all, such as sea urchins and aphis. Moreover, a part of the animal kingdom is hermaphroditic, truly bisexual. For them, homosexuality is not an issue."

—Petter Bøckman^[3]

Animal 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 observed in close to 1500 species, ranging from primates to gut worms, and is well documented for 500 of them.^[5][6]

Homosexuality in animals is seen as controversial because some assert it points to the naturalness of homosexuality in humans, while others counter that it has no implications and is nonsensical to use animal behavior to justify what is or is not immoral.^[7][8] Animal preference and motivation is always inferred from behaviour. Thus homosexual behaviour has been given a number of terms over the years. The correct usage of the term homosexual is that an animal exhibits homosexual behaviour, however this article conforms to the usage by modern research^{[9][10][11][12]} applying the term homosexuality to all sexual behaviour (copulation, genital stimulation, mating games and sexual display behaviour) between animals of the same sex.

This is an incomplete list, which may never be able to satisfy certain standards for completeness.

Revisions and sourced additions are welcome.

[edit] Selected images

The asexual, all-female Whiptail lizard species Cnemidophorus neomexicanus (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males, C. inornatus (left) and C. tigris (right). Research has shown that simulated mating behavior increases fertility for Cnemidophorus neomexicanus. One female lies on top of another, playing the role of the male, the lizard that was on bottom has larger eggs. The lizards switch off this role each mating season.^[13]

The head of Darner dragonfly (Basiaeschna janata). Male homosexuality has been inferred in several species of dragonflies. A survey of damsel and dragonflies reveals characteristic cloacal pincher mating damage in 20–80 percent of the males indicating a fairly high occurrence of sexual coupling between males.^[14][15]

[edit] Mammals

Main article: List of mammals displaying homosexual behavior

[edit] Birds

Main article: List of birds displaying homosexual behavior

[edit] Fish

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.^[16]

• Amazon molly^[17]
• Blackstripe topminnow^[18]
• Bluegill Sunfish^[19]
• Char^[20]
• Grayling^[16]
• European Bitterling^[21]
• Green swordtail^[22]
• Guiana leaffish^[23]
• Houting Whitefish^[24]
• Jewel Fish^[25]
• Least Darter (Microperca punctulata)^[26]
• Mouthbreeding Fish sp.^[27]
• Salmon spp.^[28]
• Southern platyfish^[29]
• Ten-spined stickleback^[30]
• Three-spined stickleback^[30]

[edit] Other vertebrates

• Anole sp.^[31]
• Appalachian Woodland Salamander^[32]
• Bearded Dragon^[33]
• Black-spotted Frog^[34]
• Broad-headed Skink^[35]
• Checkered Whiptail Lizard^[33]
• Chihuahuan Spotted Whiptail Lizard^[33]
• Common Ameiva^[33]
• Common Garter Snake^[36]
• Cuban Green Anole^[31]
• Desert Grassland Whiptail Lizard^[33]
• Desert Tortoise^[37]
• Fence Lizard^[33]
• Five-lined Skink^[35]
• Gopher (Pine) Snake^[38]
• Green Anole^[31]
• Inagua Curlytail Lizard^[33]
• Jamaican Giant Anole^[31]
• Laredo Striped Whiptail Lizard^[33]
• Largehead Anole^[31]
• Mountain Dusky Salamander^[32]
• Mourning Gecko^[39]
• Plateau Striped Whiptail Lizard^[33]
• Red Diamond Rattlesnake^[40]
• Red-tailed Skink^[35]
• Side-blotched Lizard^[33]
• Speckled Rattlesnake^[41]
• Tengger Desert Toad^[42]
• Water Moccasin^[43]
• Western rattlesnake (Crotalus viridis)^[44]
• Western Banded Gecko^[39]
• Whiptail Lizard spp.^[33]
• Wood Turtle^[45]

[edit] Insects and other invertebrates