Why is one ear higher than the other on an owl?

Having asymetrical (ear openings in different places on the skull) ears allows owls to accurately triangulate the location of their prey. Sounds reach each ear at different times. Additionally, they can actually change the shape of the ear opening, including closing it. Barn owls have the best hearing of any animal ever tested and can strike and kill prey solely on sound alone. Great Grey Owls easily strike and kill rodents that move under the snow. This is all possible because of the triangulation of sound they can do with their asymetrical ears.