Can animals be gay? Same-sex behavior is natural

Two dolphins swim in a pool
Photo: Shutterstock

Can animals be gay? It’s a common question. Some people want animal sexual behavior to help them decide what’s “natural” when it comes to sex and attraction. Others argue that we can’t apply human labels of sexual orientation to non-human animals.

Some anti-LGBTQ+ activists call homosexuality “unnatural.” Some pro-LGBTQ+ advocates have mentioned same-sex animal behaviors in court briefings to support overturning sodomy laws and legalizing same-sex marriage. Other advocates have said that human LGBTQ+ rights shouldn’t depend on what non-human animals do.

Regardless, the topic is fascinating and demonstrates how queer the wild animal kingdom is.

Can animals be gay?

In short, yes. Same-sex behaviors in animals have been documented early in human history. Aristotle (384–322 BC) observed it in pigeons, partridges, and quails; the Egyptian writer Horapollo (circa 4 AD) observed it in partridges; and animal researchers throughout history have observed such behaviors in many other animals as well.

However, scientists don’t call animals “gay,” “lesbian,” “bisexual,” or “queer” because the word connotes a human sexual orientation with strong cultural and political implications that are irrelevant to non-human species. Instead, most scientists will say that animals exhibit “same-sex behaviors” or “homosexual behaviors.” Scientists use these phrases to avoid “anthropomorphizing” animals and seeing them as “imperfect copies of humans,” biologist Marlene Zuk explained.

Same-sex behaviors have been observed in over 1,500 species in every major animal group and significant geographic region worldwide — including birds, insects, primates, reptiles, fish, invertebrates, and ocean mammals — according to a 2009 University of California study. These behaviors can include sexual and genital contact; courtship, affection, pair-bonding behaviors (like hugging, nuzzling, licking, and grooming); and parenting offspring.

While exclusive homosexual orientation has been observed in about 10 percent of male domesticated sheep, researchers rarely watch animals long enough to say whether they have lifelong sexual orientations. That’s because animal observation is a costly and time-consuming process.

Researching same-sex behaviors in animals can be difficult


Researching animal sexual behaviors involves a lot of sitting around and watching animals not have sex. Bad weather and poor visibility can limit a researcher’s ability to observe animals, especially among nocturnal, arctic, or deep sea creatures.

Some animals are solitary and non-social (like bears and scorpionfish) or live in large sprawling groups (like ants and birds), making it potentially challenging to observe the sexual behavior of individual animals. Also, because it’s difficult to tell the gender of some animals, some scientists have witnessed homosexual behaviors and mistakenly categorized them as heterosexual, incorrectly presuming the genders of whichever animals exhibit dominant or submissive behavior.

In other instances, heterosexual bias has caused some animal researchers to assume all animals are heterosexual until proven otherwise, according to biologist Bruce Bagemihl. Some researchers have ignored or didn’t report same-sex behaviors because they saw them as “meaningless,” as a one-off “curiosity,” or a “glitch.” Some researchers have written off such behaviors as instances of “mock,” “pseudo,” or “practice” courtship. Other researchers have been personally offended by seeing majestic animals exhibit same-sex behaviors, viewing these behaviors as shameful, a “nuisance,” or unworthy of legitimate research.

Other researchers have avoided the topic of homosexual behavior in animals altogether over fears of mockery or unwanted scrutiny by colleagues and the public. Scientists who have published research on homosexual activity in animals have faced accusations that a personal or political agenda has compromised their work, whether the researchers self-identified as LGBTQ+ or not.

As a result, there are likely far many more animals that exhibit same-sex behaviors than scientists currently realize. But because few animal researchers get to observe creatures throughout their entire lifespan, researchers must make inferences about animals’ sexual activity by singular observations of their behavior over a certain period.

Bisexual animals may be the majority

Some scientists presume that same-sex behaviors may be a part of an animal’s numerous lifelong behaviors. That is, animals may exhibit same-sex behaviors at some points of their lives and different-sex behaviors at other points, making them “bisexual” in human terms and giving them greater overall chances for survival and reproduction. However, other scientists see this presumption as possibly heterocentric or even homophobic since it doubts that some animals may have an exclusively homosexual orientation.

Others point to animal bisexuality as proof that bisexuality is actually the default sexual orientation of animals and that modern-day humans have only assumed that heterosexuality is the default sexual orientation of all living things.

If gay animals exist, does that mean homosexuality is “natural?”


Whether same-sex sexual activity in animals proves that homosexuality in humans is “natural” depends primarily on one’s feelings towards nature or homosexuality. Some say same-sex animal behaviors validate homosexuality as natural, inborn, and acceptable in humans. Others say animal same-sex sexual activity proves that homosexuality is a “non-human” trait of “uncivilized” “lower animals” that should be rejected in humans.

The word “natural” literally means “existing in or caused by nature; not made or caused by humankind.” But it’s a relative term with no agreed-upon scientific definition. Humans are animals and do many activities that aren’t otherwise found in nature — like watching television or driving vehicles — but no one calls these actions “unnatural.” On the other hand, some animals rape and eat their young, but few would argue that these “natural” behaviors should be accepted among humans.

Perhaps the more scientific question is why homosexual animal behaviors persist. After all, such behaviors don’t neatly fit the Darwinian view that all animal behavior is geared toward survival or reproduction. That view states that traits and genes that don’t aid survival or reproduction shouldn’t persist throughout generations.

Researchers have deduced that same-sex animal behavior serves several functions, including reproductive advantages. But same-sex behaviors may have different causes and consequences in individual animal species. It could even be that some animals consciously choose to participate in these behaviors rather than having an inborn orientation toward them.

What evolutionary reasons drive same-sex animal behaviors?

In lab settings, researchers have found that animal homosexuality is more likely to occur in animals with differing levels of prenatal hormones; essential sex hormones, like testosterone, estradiol, and estrogen; or neurotransmitters like serotonin and dopamine. However, there is a difference between same-sex activity observed in laboratory settings, in captivity, and the wild.

Researchers believe any underlying biological, hereditary, and genetic bases for animal homosexuality are likely tied to multiple alleles (or locations) on different DNA strands throughout an animal’s genetic code. This, and the fact that these gay genes are only activated under certain circumstances (something known as “epigenetics”), may calm fears that anti-LGBTQ+ forces would try to eradicate “gay genes” in humans if they found an underlying genetic basis for it in nature.

Some animal homosexuality is only exhibited under certain conditions, such as when among populations that have far fewer of the opposite sex (something occasionally referred to as “the prisoner effect.”) or in laboratories or captivity where the number of possible sexual partners is limited.

One epigenetic theory, championed by evolutionary biologist James O’Keefe, notes that “gay genes” in animal offspring seem to be expressed if a mother experiences severe prenatal stress or gives birth to a high number of male offspring. In those cases, homosexual offspring help ensure that the family doesn’t have too many mouths to feed or multiple males fighting over female mates. These two issues can reduce a family’s overall health and cohesion. Put another way, gay offspring can make animal families more harmonious and capable of surviving.

Researchers have found that same-sex animal behaviors may have the following benefits:

  • Social cohesion – It can help form tighter social bonds and improve group strength.
  • Stress relief It can de-escalate tension and reduce the likelihood of conflict among individuals and groups.
  • Sexual competition – Mating with same-sex competitors can exhaust them, negatively affecting a rival’s ability to mate successfully with other different-sex partners.
  • Reproductive strength – Co-parenting offspring gives newborns greater chances of survival.

So, which animals are gay?

Shutterstock A butterflies kiss, in a garden

Same-sex sexual activity has been observed in males and females in over 1,500 animal species throughout the animal kingdom. Such sexual activity has been seen in penguins living in the Central Park zoo, giraffes rubbing their necks in Africa, Japanese macaques grooming members of the same sex, bottlenose dolphins forming same-sex pairs in the middle of the ocean, and other animals demonstrating homosexual behaviors around the world.


Same-sex behaviors have been observed in over 500 bird species, including birds of paradise, chickens, doves, flamingos, geese, gulls, herons, jays, magpies, owls, ostriches, parakeets, parrots, ravens, swallows, turkeys, woodpeckers, and other species. Below are some bird species and descriptions of their same-sex behaviors.

  • Black swans – An estimated 25% of all black swan pairings are male-male. They mate with females or steal their nests and then drive the females away. Their offspring survive more often than those of different-sex pairs.
  • Female Laysan albatrosses – They mate with males and then co-raise the offspring together, taking turns hunting for food to feed themselves and their young.
  • Black-browed albatrosses – Global warming has killed many females, resulting in more male-male sex pairs in the wild.
  • Mallards – Wild ducks have high rates of male-male sexual activity.
  • American white ibis – In lab settings, exposure to the environmental pollutant methylmercury increased homosexual behaviors in males.
  • Penguins (African, Chinstrap, King, Humboldt, and Magellanic) – These birds have been observed forming male-male pairs and raising eggs together.
  • Griffon vultures – Male-male pairs in captivity have nested and raised eggs together.
  • Pigeons – Same-sex pairs nest together.

Land mammals

Same-sex behaviors have been observed in many land mammals, including antelopes, bats, bears, buffalo, cats, chipmunks, deer, donkeys, foxes, hamsters, hedgehogs, horses, hyenas, gazelles, goats, guinea pigs, koalas, mice, moose, otters, pigs, rabbits, raccoons, seals, shrews, squirrels, tigers, wallabies, wolves, zebras, and numerous other species. Below are some land mammal species and descriptions of their same-sex behaviors.

  • American Bison – Male pairs have been observed engaging in courtship, mounting, and full anal penetration. Females in heat also mount each other.
  • Bats – Over 20 species have been observed grooming, licking, masturbating, and mounting in reciprocal and forced sexual activity.
  • African and Asian elephants – Their same-sex bonding includes kissing, intertwining trunk, placing trunks in each other’s mouths, mounting, and forming same-sex pairs that last years.
  • Giraffes – Many male pairs engage in “necking” (rubbing their necks together), caressing, courting, mounting, and climaxing.
  • Koalas – Females forcibly mount other females in the wild.
  • Marmots (Olympic and hoary) – Female pairs, especially ones in heat, nuzzle, touch noses and mouths, and mount one another.
  • Lions – Males in the wild and females in captivity affectionately nuzzle, caress, mount, and thrust together.
  • Spotted hyenas – Females mount one another.

Insects and arachnids

Same-sex behaviors have been observed in at least 110 species of insects and arachnids, including ants, antlions, aphids, beetles, butterflies, caterpillars, cockroaches, dragonflies, flies, locusts, mites, mosquitoes, moths, snails, stink bugs, termites, wasps, and numerous other species. These have occurred mostly among males exposed to female pheromones in lab settings. However, a 2013 study suggested that insect same-sex behaviors are largely understudied.

  • Bed bugs – Males are attracted to newly fed bed bugs regardless of sex and will forcibly penetrate their abdomens with their needle-like penises, sometimes injuring the abdomens of males. Male bed bugs also excrete alarm pheromones to stop such potentially lethal same-sex pairings.
  • Dragonflies – Studies conducted in the early 1990s found many males had evidence of head damage. Such damage is caused when a male clenches its cloacal pinchers sexually upon the head of another male.
  • Fruit flies – Genetic manipulation can cause male fruit flies to participate in same-sex courtship and mating behaviors, including licking a male’s genitals.


Animal behaviorist scholar Paul Vasey has suggested that same-sex behaviors among primates may just be sexually pleasurable without any adaptive payoff. But others suggest that it creates strong social bonds that help primates live more peaceably and makes them more willing to defend one another.

  • Bonobos – The males and females of this great ape species are considered fully bisexual, with 60% of all female sex pairings being same-sex. Males and females use genital rubbing, presumably to divert attention and defuse conflicts.
  • Gorillas – In the wild, all-male bachelor packs exhibit social bonding behaviors. Female mountain gorillas do as well, possibly to establish dominance, affiliation, reconciliation, or arousal.
  • Japanese macaques (snow monkeys) – Males and females frequently form affectionate same-sex pairings that last days or weeks, though rates vary between different groups.
  • Orangutans – Males have exhibited homosexual behavior in both the wild and captivity.

Fish and water mammals

In some fish species, females have shown more significant attraction to non-dominate males seen nipping at the genitals of other males. Researchers think females may get aroused by this behavior or see it as a display of male sexual prowess.

  • Dolphins – Amazon river dolphins sometimes have group sex with three to five individuals using their flippers, fins, snouts, and blowholes to stimulate each others’ genitals. Same-sex bottlenose dolphin pairs rub their genitals together or insert their snouts into one another’s genital slits or anuses. They’ve even engaged in cross-species homosexual sex with Atlantic spotted dolphins as a possible way to avoid combat, a 1997 study found.
  • GuppiesA 2004 study found that guppies raised in predominantly male environments exhibit more homosexual behaviors than those in mixed-sex environments.
  • Gray whales – These whales form homosexual relationships with up to two partners and have been observed hunting together and swimming while touching fins (a possible sign of affection).
  • Walruses – Males demonstrate predominantly homosexual behavior until they reach sexual maturity. After that, they primarily become bisexual, forming affectionate same-sex partnerships while having sex with females only during mating season.

Reptiles and amphibians

Same-sex behaviors have been observed among varieties of frogs, geckos, lizards, salamanders, skinks, snakes, toads, tortoises, turtles, and numerous other reptile and amphibian species. Below are some reptile and amphibian species and descriptions of their same-sex behaviors.

  • Aldabra giant tortoises – Scientists found that the world’s oldest known tortoise had spent years mating with a male tortoise that researchers initially mistook for a female.
  • Geckos – Two common species (phelsuma laticauda and phelsuma cepediana) have exhibited same-sex behaviors.
  • Whiptail lizards – Female lizards with low estrogen levels have been observed engaging in “masculine” sexual roles. In contrast, ones with high estrogen levels engage in “feminine” sexual roles, according to a 1990 article.

What about transgender, intersex, or asexual animals?


While this goes beyond the scope of this article, researchers have observed animals capable of changing genders. Male clownfish, in particular (pictured above), can carry both female and male reproductive organs. Sexually immature males can turn into females if the alpha female dies.

Intersex animals that have a combination of male and female anatomies — such as coral, Pacific spadenose sharks, and some lionesses — have been observed in the wild. Some animals also have working sets of both male and female genitalia, though this is a form of hermaphroditism that isn’t the same as being intersex. Some bees, starfish, snakes, and wasps have also demonstrated asexual behaviors, and other animals — such as Komodo dragons, starfish, and turkeys — can reproduce asexually.

Are there any books or films about gay animals?

Numerous books discuss same-sex animal behaviors, but while some TV nature programs have briefly covered the topic, there seem to be no feature-length documentaries about the issue. Here are three books about same-sex animal behaviors.

  • Biological Exuberance by Bruce Bagemihl (1999) – Bagemihl, an animal researcher who is gay, shares his extensive piecemeal research showing how biologists’ biases have helped hide animal homosexuality for over 150 years.
  • Sexual Selections: What We Can and Can’t Learn About Sex from Animals by Marlene Zuk (2002) – Zuk argues that anthropomorphism and gender politics have colored human understanding of the natural world, but humans must learn to see the animal world on its own terms.
  • And Tango Makes Three by Justin Richardson and Peter Parnell (2005) – This illustrated children’s book tells the real-life story of Roy and Silo, two male chinstrap penguins in New York City’s Central Park Zoo, who raised a young chick named Tango. It’s just one of many children’s books about gay animals.
  • Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People by Joan Roughgarden (2013) – A book that re-examines mainstream understanding of sex, gender, and sexuality in animals by applying feminist, gay, and transgender critical lenses onto animal behavioral research.
  • Queer Ducks (and Other Animals): The Natural World of Animal Sexuality by Eliot Schrefer, illustrated by Jules Zuckerberg (2022) – An illustrated young adult nonfiction that combines humor with accessible science on same-sex behaviors observed in animals.

In conclusion

Animal sexual activities show a range of heterosexual, homosexual, bisexual, intersexual, asexual, promiscuous, monogamous, and polygamous behaviors. Whether this says anything about human nature is debatable, but it validates the notion that humans aren’t the only queer animals in the animal kingdom.

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