The Arnhem Zoo Chimpanzee Colony
The Arnhem Zoo chimpanzee colony was established in 1971 with the object of providing a habitat which would both be suitable and large enough for the maintenance of a chimpanzee group of natural composition. It was hoped to give the animals  the opportunity to behave as naturally as possible with the minimum of interference by humans. At the same time studies were initiated on the group's social behaviour. An overview of developments up till 1985, with special emphasis on husbandry and veterinary matters is given by Adang et al. (1987). More information about research on the Arnhem Zoo chimpanzee colony here. Bert Haanstra made a famous film on the daily life of the Arnhem chimps. Two books have been written on the Arnhem chimpanzees: "Chimpanzee Politics" (1982, revised edition 1998) by Frans de Waal and "The most powerful chimpanzee of the Netherlands" (1999) by Otto Adang.

The animals at Arnhem are released into the outside enclosure, an island of c.0.7 ha, at around 09.30 hours each day that the ambient temperature is well in excess of 10C. The outside enclosure contains wooden climbing structures and trees, most of which are protected by electic wires. A water filled ditch and plant border around most of the enclosure's perimeter protect the apes from contact with the public. They spend the night in night cages, where they also receive food individually every morning and evening.

Although the sex ratio of the Arnhem colony is heavily in favoiur of females, the group comes close to the age-sex composition and size of groups in the wild. The general behaviour of the Arnhem colony also appears quite natural. A closer contact with human beings is inevitable in captivity but contact with keepers is kept to a minimum and as a rule the colony members pay little attention to people or activities outside their enclosure.

The captive chimpanzees do not, of course, need to spend a large part of the day searching for food but they do show foraging behaviour, eating grass, collecting acorns and beech nuts or fallen green leaves and trying to obtain leaves from the protected trees by jumping and climbing or by throwing sticks. The captive chimpanzees have more time for social interaction, such as grooming and playing than their wild counterparts. Most of the time the group is quiet and peaceful.
The most important difference between the Arnhem colony and a wild one is, of course, space. The enclosure is sufficiently spacious to enable individuals to flee or retire into a quite corner but all the animals are permanently within hearing distance and may, intetionally or otherwise, become involved in any of the activities of the others. One consequence of this restriction on movement, is that the Arnhem females seem to be less fearful of males than those in the wild. It is not uncommon to see a female solicit and receive support from several others against one of the males.
Since no neighbouring communities exist, migrations and intercommunity interactions are, of course, impossible. Within the group, however, spatial separation does occur, and temporary subgroups are formed and disbanded.

Based on extensive DNA-testing, it has been decided to breed with the Western subspecies of chimpanzee in Europe, which outnumber all other subspecies in European zoos, alongside a modest European breeding programme for the Central subspecies. Based on these compulsory guideliness in 2015 Arnhem Zoo has sterilized two chimpanzee males which do not belong for a full hundred percent to the Western subspecies.
Arnhem Zoo
If you want information about Arnhem Zoo, you should contact them directly. Burgers' Zoo (as it is officially called) is not just famous for its chimpanzee colony, but also for its innovative eco-displays, notably Burgers' Bush, Burgers' Desert and Burgers' Ocean.

© Otto Adang