Owl skull. Coloured X-ray of an eagle owl's skull (Bubo sp.), from beneath. This owl has excellent binocular vision. Bony structures (sclerotic rings, brown, upper left and right) surround the eyes and prevent them from moving in their sockets; instead the owl moves its head. The ears are located on either side of the head, behind the eyes. The eagle owl hunts mainly at night and has excellent hearing. Its facial feathers (not seen) funnel sound waves towards the ears, whilst the downward-pointing beak (lower frame) increases the surface area over which the waves are collected. Semicircular canals (pink, top centre) maintain the owl's balance.