Humane, effective, maintenance-free electronic bird repeller keeps birds away from your property without messy or expensive chemical solutions. Ultrasonic sounds discourage birds but are silent to most humans. Use it to repel pigeons, woodpeckers, swallows, starlings, sparrows, and other creatures. Coverage: Up to 900 sq ft. Use on balconies, decks, yards, lawns, gardens, porches, buildings, greenhouses, and more. AC adapter included with 30' extension cord, or may be operated with 4 "C" batteries in motion sensor mode.