They surely could, but the management in the Tierpark thinks that too much stuff into an animal enclosure is no good and distracts the visitors from the animals. It`s horrible. Many of the enclosures are spacious but so barren that it`s unbelieveble. Barren enclosures are not that bad for ungulates, but for monkeys, it`s just awful. This is one of the many reasons why I seriously hope that the director of the Berlin Zoos will be kicked out as soon as possible for all the mismanagement he`s responsible for. He`s pretty young (early 50`th) and I truly hope the animals don`t need to wait until he retires.