Media playback is unsupported on your device Media caption London Zoo's all-girl gorilla enclosure is expecting a new arrival

London Zoo is introducing a new male to its group of gorillas.

They have been without a troop leader since the last male died in March and the zoo says Kesho will be crucial to the stability of the group.

But it says introducing a silverback from Dublin Zoo will be risky.

Female gorilla Mjukuu is pregnant and due to give birth in a couple of months. If the zoo waits until then to introduce a new male, there is a high risk he will kill the baby.

'Tension and stress'

Dr Kirsten Pullen, who is an expert on gorilla behaviour said: "It's the bond between the female and the silverback that maintains the bond of the group.

"When females are left on their own, there is an increase of tension and stress as there isn't a strong female to female bond. Without a male, the females often end up fighting and have to be separated."

But it is common for male gorillas to kill the offspring of other silverbacks and it happens both in captivity and in the wild.

To limit the risk of this happening, the zoo plans to introduce 11-year-old blackback Kesho into the group by the end of the month.

We're confident he's going to be the right gorilla for our girls David Field, London Zoo

But there is still a risk the baby will be killed by this new arrival.

David Field, the Zoological Director of London Zoo, said: "The introduction of a new male into this environment is very precarious.

"It carries significant risk for the death of the infant when it's born later this year. But we believe we are making the right decisions based on the expert opinions we have received."

London Zoo says it has carefully chosen Kesho to make sure he integrates well into the group - hopefully adopting the new arrival and mating with the other females.

The zoo says it has chosen Kesho because is still a young blackback who will develop into an alpha male silverback and take on the leadership of the group.

Mr Field said: "We've made sure we've got a very socially groomed gorilla - one who knows how to live in a family situation.

"Crucially he's not too old, so he's very playful. We're confident he's going to be the right gorilla for our girls."

Kesho has grown up with his family in Dublin Zoo and keepers hope he will provide a new role model for the new arrival.

Kesho is expected to arrive at London Zoo by the end of the month.