Take a section of tape and stretch it tightly between stakes placed throughout your garden, or at either end of the row. Both the sound made by the tape blowing in the wind, and the reflection of sunlight hitting the tape, causes critters to scurry elsewhere. Thread a piece of fishing line through the hole and tie a knot. Hang the CD's in areas where birds and pests are a problem.
Good choices are in fruit trees, berry bushes, and vegetable gardens.
The wind blows the CD and as sunlight hits it, light is bounced back into the eyes of would-be attackers, and scares them away.