A new study says that penguins who engage in same-sex mating displays are flirty, rather than gay.

Incidences of homosexuality in the species have been well-documented and one male penguin couple at San Francisco Zoo were together for six years before splitting up in 2009.

However, researchers at the Centre for Functional and Evolutionary Ecology in Montpellier, France, say that the birds could be engaging in same-sex mating rituals because there were too many males or because the males have too much testosterone.

They found evidence of same-sex penguin couples in the wild but discovered that over time, the vast majority of the birds formed heterosexual relationships.

More than a quarter of the birds surveyed in one king penguin colony engaged in mating displays with the same sex.

However, only two couples – one male and one female – bonded enough to learn each other’s calls.

One theory is that penguins develop closeness with the same sex because there are not enough birds of the opposite sex.

Another theory said that penguins find it difficult to tell the difference between males and females and ended up pairing off randomly.

Director of Research Professor Stephen Dobson told the BBC that the second theory was unlikely.

“I found that the rate of homosexually displaying pairs was significantly lower than one would expect by chance,” he said.

Referring to the two couples who learned each other’s calls, Professor Dobson added: “So these pairs can bond. But, bonded pairs can split up if one finds a more preferred partner.”

The study was published in the journal Ethology.