One of the 'gay' penguins (R) looks at his fellow female penguins from Sweden (from L) in the penguin enclosure at the zoo in Bremerhaven, Germany. The zookeeper's attempt to breed offspring from the endangered species of Humboldt penguins has failed again after female penguins from Sweden were placed in the enclosure.
Credit: AFP/Ingo Wagner
Buddy and Pedro are in a committed relationship with one another. Late last year these two cute-as-a-button African penguins at Toronto Zoo in Canada were forced apart by zookeepers. This is because Buddy and Pedro are both males and their keepers are desperate for the pair to breed with female penguins because of the species' endangered status.
Outrage ensued, as protesters cried "blatant homophobia" and demanded the penguin couple be reunited. The zoo has said it will reunite them early this year, but only once they successfully mate with the females.
Whether or not they will produce offspring willingly with the females is another matter. Penguins tend to mate for life. In 2004, male pair of chinstrap penguins at New York City Zoo was given an egg to raise and hatch after they appeared to try 'hatching' a rock as if it were an egg. The couple, Roy and Silo, have since successfully raised little Tango as their own, despite later separating.
In 2009, a pair of male Humboldt penguins at Bremerhaven Zoo in Northern Germany resisted mating with females in favour of raising an abandoned egg together. When isolated with females, the males reportedly pined for their mates.
There are many more examples of homosexual pairings between animals, but so far research into it has been scarce. Nearly 500 species of animals (ranging from mammals through to insects) have been observed performing homosexual behaviour, according to Aldo Poiani, a biologist at the University of Melbourne.
In addition to penguins, he says, koalas, flamingos, giraffes, monkeys, killer whales and dolphins are on list. In some cases, the animals commit themselves to a same-sex partner for life (like penguins), although in other species it appears that they have no preference, but rather act 'bisexually'.
In September 2011, scientists led by Hendrik Hoving from the Monterey Bay Aquarium Research Institute in California described a deep-sea squid (Octopoteuthis deletron) that would happily mate with either sex. The media was quick to announce the discovery of a 'gay' squid - although the scientists involved insisted that this wasn't an indication of its sexual preference but rather a survival mechanism. Because it inhabits the darkest depths of the ocean, if it didn't mate with every potential mate that passed by, the species wouldn't survive.
"These squid only reproduce once in their lifetime, so they are under a time constraint. They probably don't spend a lot of time trying to figure out what sex their partner is," says Hoving.
Curiously, not all species exhibit homosexual behaviour of both the male/male and female/female kind. According to a 2006 report co-authored by Geoff McFarlane from Australia's University of Newcastle in New South Wales, a species of small shorebirds called black-faced sheathbills are only interested in female/female (as well as male/female) sexual encounters.
"Homosexual behaviour occurs in over 130 species of birds, yet explaining its maintenance in evolutionary terms appears problematic at face value, as such sexual behaviours do not seem in immediate pursuit of reproductive goals," McFarlane and colleagues wrote in the journal Animal Behaviour in late 2010.
