"As protected conservation areas become smaller, lions are increasingly coming into contact with human populations, which are expanding to the boundaries of these protected areas," says Dr. Neil Jordan, a conservation biologist from UNSW's Centre for Ecosystem Science.
The reason is quite interesting. When they make "eye-contact" with the butt eyes, the lions will assume that the prey has seen them and will decide to move on, without a surprise element. The lions will think their intended prey has seen them.