A zoo was forced to put up an electric fence to protect builders from baboons angry at the demolition of their home.
The 120-strong troop of baboons has lived in the two-storey building at Knowsley Safari Park, in Merseyside, for the past 35 years.
But they reacted angrily when builders moved in to knock it down and replace it with a new compound.
Safari Park general manager David Ross said: "The problem with animals is that you can't consult with them and tell them that they'll have new deluxe accommodation within a few weeks.
"We just had to go in there and demolish the building to make way for the new structure, although the work was specifically scheduled for high summer when baboons prefer to sleep outside in the trees.
"Nevertheless, as soon as they saw what was happening the troop got very agitated and I could hear them barking and chattering all through the night."
Project manager Geoff Ames said it was the most unusual project he had worked on.
He added: "Because we're effectively in a cage and the animals are free to roam around us we do feel as though the roles are reversed and we are the exhibit.
"However, we're grateful for the protection because the baboons were obviously not very happy about the demolition."