More than half of the penguins at Irish aquarium are now in same-sex pairs and are raising chicks together

More than half the penguins at an Irish aquarium are in same-sex relationships, it has been revealed.

Eight of the 14 residents of theDingle Oceanworld Aquarium's penguin enclosure have a gay or lesbian partner.

In a bizarre coincidence, keepers at the County Kerry aquarium say the number of same-sex couples has rocketed since Ireland legalised gay marriage in 2015.

Pairs of female penguins have even been known to raise a chick together after producing one with a temporary male partner, theIrish Mirrorreported.

Manager Louise Overy told the newspaper: 'We have two homosexual pairs and two lesbian ones.

'You cannot tell a male penguin from a female by their sexual organs so the only way we know is when we see them mating and not producing chicks.'

The four gay couples now at the aquarium mark an increase from just one - called Penelope and Misty - five years ago, she said.

The prospective partners will 'woo each other' with stones which are used to construct a nest, she added.

Same-sex penguin couples have previously been known to rear younglings at zoos including in Berlin and New York.

Unlike many mammal species, male and female penguins take on the same parenting roles, and share parental duties 50-50.

'There is no real difference when it comes to breeding behaviours between males and females,' a Sea Life expert said last year.

So it 'is common to have male-male or female-female showing courtship and breeding behaviour.'

According to one 2010 study penguins may indulge in some same-sex flirting because they are 'lonely'.

Another theory in the study was that penguins may pair up with other males because they could not tell the difference between the sexes and so paired at random.

Gay 'flirting' could also be due to high levels of testosterone within the colony among males.

In 2004, gay penguin couple Roy and Silo were the subject of a feature on their relationship which began in 1998 at New York's Central Park Zoo.

The male penguins engaged in the same mating rituals as straight penguin couples, and, after zoo staff saw them trying to hatch a rock, they were given a baby named Tango.

The story was made into a children's book in 2005 titled 'And Tango Makes Three.