He has yet to approach any of them, but the females have been showing growing interest.
Zaire, who is said to be still pining for Jomie, was featured on BBC television recently amid claims from the animal rights campaign group Born Free that she is exhibiting signs of stress. Nick Lindsay said: "We had to be a little cautious when reintroducing Zaire to the group.
"Zaire had become the dominant gorilla in the absence of a male. She had to be temporarily segregated from the others when she began to bully another female.
"However, with the presence of our new male she has integrated back into the group successfully."
The arrival of Jock is symbolic of the efforts being made in the capital to conserve this endangered species. Gorillas and other great apes are not only threatened by habitat loss, but by the growing market in bushmeat.
The trade - featured in yesterday's Evening Standard - is becoming a major international issue with bushmeat being sold in London. Today, Barry Gardiner MP and Robert Evans MEP are launching the UK Bushmeat Campaign at Westminster, a coalition of 30 conservation groups.
