CDs scare away the birds

When left unattended, the birds would swoop to the table and feed on the food of customers who had left to buy their drinks. These birds are very hungry creatures and they will come by the dozens. Whenever the diners left the tables with leftover food more birds will come and happily feed themselves. The situation could sometimes get out of control and the birds after their feed would poo on the tables and chairs.
The coffee shop supervisor was so fed up with these creatures that he resort to tying the used CDs on to the ledge to frighten away the birds. I was told that the CDs are like mirrors and the reflection of the birds plus the movement scares away the pests. Now, the birds stood on the side on the floor,away from the CDs and hope someone will throw some scraps of food to them.