A "super group" of 22 chimps has finally joined together at Edinburgh Zoo.
Eleven new chimps have integrated with the existing 11 resident chimps in the Budongo Trail.
The trail is the world's largest chimpanzee enclosure, according to officials at Edinburgh Zoo.
It has taken almost six months to complete the integration of the two groups as chimps live in complex communities.
Due to hierarchical groupings, keepers closely observed the status level of every chimp in the new group and correlated this to the nearest in status in the existing one.
Jo Richardson, head keeper at Budongo Trail, said: "It is important for the success of the integration to know individuals well as chimps have a lot of group politics and social dynamics, and are an extremely intelligent and volatile species.
"This has been the biggest challenge and achievement for all the team at Budongo Trail so far, as this is the largest integration of chimps we have ever undertaken.
Ms Richardson said the resident chimps have individual characteristics and when a new group is brought in it must be handled in the right way to ensure that no chimp's status is challenged initially as the two groups come together.
"So you start with those with the lowest status then gradually progress up the status ladder until you get to the highest level and those being the alpha males," she said.
"This is done at the chimps' pace to ensure all group members have a chance to settle and integrate well with hopefully minimal aggression, as chimps will sort out hierarchy and dynamics through both affiliative behaviour and sometimes fighting."
Chimp hierarchies do not have a strict "pecking order", but are complex, fluid, flexible, and change often.
Rank depends on personality as well as strength.
Highly intelligent chimpanzees are the closets living primate to humans, sharing 98% of their DNA and are known to live up 60 years in captivity.
Originally from Beekse Bergen Safari Park in Holland, it is hoped that the 11 new chimps will be an important part of Edinburgh Zoo's contribution to the captive breeding programme which is now concentrating on the endangered sub-species, the Western chimpanzee (Pan troglodytes verus).