This is the best all around product to keep blue herons, king fishers and other persistent fish eaters away from your pond. The Scarecrow senses both heat and movement, then releases a noisy, three second burst of oscillating water. This is a harmless method of keeping fish eating wildlife away from your pond. Uses only two cups of water, with each burst. Hooks up to your garden hose and sensitivity of sensor can be adjusted for readings up to 35 feet away. Batteries are not included.