In the past, it was claimed that penguins could not discern between the sexes because they looked alike. Male pairs in zoos in the US and Germany have hatched and reared ‘adopted’ chicks.

However the new study by the Centre for Functional and Evolutionary Ecology in Montpellier, France found that the penguins are only pairing up with other males because they are “lonely”.

There are not enough females in the colony and the males have high levels of testosterone, which drives them to engage in mating displays – even if it is with other males.