In Hanover zoo in the aviary with orangutans put machine with nuts. To get the nuts, monkeys were required to complete a chain of successive actions. How it ended, see below.
Orangutan Zoo Hanover presented their own machine with nuts. (REX FEATURES)
Before placing the bottom nuts, where they already can get it, orangutans have to spend a sequence of actions. (REX FEATURES)
As can be seen from these photographs, monkeys were able to find the right solution to the problem. (REX FEATURES)