@snowleopard: Yes, the electrified fence is the only barrier. During the first year the gorillas lived in this enclosure, one summers night Samson somehow escaped over/through the fence in the back of the enclosure. He quickly discovered that he did not enjoy life on the outside, so he attempted to get back in. When he could not he calmly made a nest of some branches and leaves and fell asleep. The next morning he was captured withour making a big fuss and transported back to the enclosure. Neither him nor the others have ever tried to escape again.
Samson is very probably the most famous animal in Denmark and quite a local hero
Oh... I remeber seeing this big guy in the tiny indoor enclosure, perhaps 150 square meters big, at Copenhagen Zoo. His big silverback turned against the visitors, probably bored out of his skull! Now he spends his time outdoors in a big enclosure! Though it took him days to dare to go out there... he was the last of the group of apes to dare to take the step into the BIG UNKNOWN... the females were much more brave than him! (All of this drama shown on Danish television.)
But now he IS out there, smelling the smells, exploring the habitat. It is so wonderful!
Ah yes, Brutalis. How could I forget? Givskud Zoo actually has a small monument in his honour (one the drinking troughs he has destroyed). And a damn good beer it is too! Quite strong...
Other famous Danish animals are the late orang-utan Charlie from Aalborg Zoo and Chieng-Mai and the other elephants from Copenhagen Zoo.
It looks like just a simple electrified mesh fence as might be used for domestic stock? If so it must be the simplest barrier anywhere for Gorillas, but apart from Samson's one escape, it is obviously very effective. It sounds as if it is more a psychological barrier for them than anything?