Animals that mate with the same sex - Whether for courting, sex, or even adoptive parenting, same-sex partnering is common in every major group of species in almost all geographic regions of the world. Take a look at which animals have been observed mating with their own sex.

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Elephants - Same-sex relationships among elephants are long-lasting, unlike their heterosexual relationships. Up to 45% of Asiatic elephants form same-sex relationships.

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Giraffes - Male giraffes are much more likely to perform mating rituals with other males than they are with females. 

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American bison - Both bulls and cattle are known for forming same-sex pairs.

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Marmots - Female marmots are more commonly known to mate with each other than with males.

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Polecats - European polecats are believed to form romantic same-sex relationships for no evolutionary purpose.

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Sheep - Between 8 and 10% of rams are attracted to the same sex and another 18 to 20% of rams are attracted to both sexes.

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Spotted hyenas - Hyenas live in a matriarchal society where females are very aggressive and routinely mate with each other. 

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Lions - Male lions will spend days together in same-sex bonding. While female same-sex relationships are common in captivity, the behavior has never been observed in the wild.

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Whiptail lizards - Whiptail lizards have an asexual reproductive system. Females increase their hormones by having sex with other females.

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Tortoises - Tortoises are regularly observed mating with the same sex. 

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Bottlenose dolphins - Bottlenose dolphins are the most-observed dolphins for same-sex coupling, which includes females partnering with each other as well as males partnering with each other.

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Amazon river dolphins - Dolphins have sex for pleasure and Amazon river dolphins have mating groups of three to five, often including one or two females.

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Bonobos - Bonobos live in a matriarchal society where most are bisexual and most sexual activity involves two or more females.

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Japanese macaques - Same-sex unions are highly common among these snow monkeys. Females will form groups and males pair off with other male monkeys of a similar age.

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Оrangutans - Same-sex bonding is a fundamental part of orangutan society, both in the wild and in captivity.

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Vultures - Male griffon vultures have been observed mating and raising adopted eggs together.

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Black swans - One quarter of all black swan couples are two males. The males sometimes include a female third partner and drive her away after she lays her eggs.

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Laysan albatrosses - After mating with males, female laysan albatrosses often pair off with each other to raise their hatchlings, possibly because there are far more females than males.

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Ibises - Scientists observed that ibises exposed to methylmercury had a significantly higher rate of mating with the same sex than those that were not.

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Mallards - Up to 19% of male mallard ducks will mate with other males after impregnating female ones.

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Pigeons - Both male and female pigeons are known to have same-sex relationships, with female pigeon pairs laying infertile eggs and attempting to nest them.

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Penguins - A number of penguin species have been observed engaging in same-sex partnerships.

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Magellanic penguins - Two male magellanic penguins raised an adopted baby penguin together in the San Francisco Zoo.

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Bats - Up to 20 species of bats are known to form same-sex relationships.

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Long-fingered bats - Male long-fingered bats from Morocco, Algeria, southern Europe, and western Iran are known to have sex with each other.

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Indian flying foxes - Male Indian flying foxes in Bangladesh, Bhutan, India, Tibet, Maldives, Myanmar, Nepal, Pakistan, and Sri Lanka are also known for having sex with each other.

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Dragonflies - Between 20 and 80% of male dragonflies couple with other males. 

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Fruit flies - Male fruit flies almost exclusively mate with other males. 

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Bed bugs - Bed bugs are attracted to any newly-fed member of their species, including members of the same sex.

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