A male gorilla living at Bristol Zoo has turned out to be female, and will now join a European breeding programme attempting to save the species from dying out.

Kukena was born at the zoo on 27 September 2011 to mother Salome and the troop's silverback Jock.

Gorillas are notoriously difficult to sex but zookeepers were convinced Kukena - nicknamed Kuki - was male.

However in the last few months experts caring for the western lowland gorilla noticed changes to her sexual organs and behaviour.

Although the discovery means that the gorilla will be separated from the troop of seven in the next few years, it is good new for the species, which is critically endangered. There are far fewer females than males in the world’s zoos making breeding programmes tricky and time consuming.