23/05/2012 12:35 BST | Updated 23/05/2012 17:21 BST

'Gay' Penguin Couple Given Egg Of Their Own

Every spring for six years Gentoo penguins Inca and Rayas have lovingly built a nest together, only to find that no eggs arrive to fill it. It doesn't seem to have dawned on the couple that both of them are male.

But after the repeated heartbreak of watching other penguins become parents and raise their young, the "gay" couple finally have something to celebrate after their keepers gave them an egg of their own to care for.