Orang utans, Jazz and Jorong, are keeping primate keepers on their toes when it comes to bedtime.
Just like naughty children the mischievous great apes have been refusing to leave their outdoor climbing frame and go inside to their internal enclosure at the end of the day.
Trainee keeper, Shaun Crompton, said: “It doesn’t matter how much we call, they don’t want to come down if the sun is shining.
“We’ve even tried to tempt Jazz down with grapes, which are her favourite food.
“But she’s been coming down, grabbing the grapes and then running back off before we’ve had chance to close the door behind her and has even started to hold the door latch so we can’t open it from the inside.”
Shaun added: “We are now working in pairs to try to trick Jazz in, so we can quickly open and shut the door when we’ve got her down with the grapes.
“With Jorong it’s slightly easier. We just turn off all the lights and pretend we’ve gone home. If he thinks no one is interested in him anymore he’ll soon come inside.”