Ours are removable but not screwed in. Being wooden huts (garden shed type) they had to be modified anyway so when we added the perches we screwed 'patches' of 1" thick planking onto the wall at each end. With a notch the shape of the cross-section of the perch cut into the top of these, the perch itself slots in very easily and comes out every time we take the flame gun to the ends to make sure no red mites have sneaked in. If I haven't explained very well I can go and take a photo if you wish.