The Sparrow "Trap Door" with Audio Module is the trap that doesn't look, or function, like a normal trap. Representing over three years of testing and development, there is a finally a humane bird trap specifically for birds trapped inside structures. The "Trap Door" was designed specifically to provide a discrete, gentle, hygenic, and cost-effective way to get small birds out of buildings.When set, the "Trap Door" is simply a welcoming platform with food. Birds stand on the platform eating happily until they press down on the perch. Suddenly, the floor gives way under them and they fall inside the ventilated box with a lid positioned securely above. When a bird is captured it will remain quiet and calm within the holding box until it can be released safely outdoors. Food and water can be left inside to protect the bird. To release the bird outside simply open the "Trap Door" lid and it will fly out. The "Trap Door" looks more like a bird feeder than a trap. Sparrows easily become accustomed to coming and going from the trap to feed. The "Trap Door" Audio Module lets you add a proprietary sparrow song which has proven to attract more birds. The call operates on an intermittent basis so birds don't get used to it. There are ten different programs to choose from. The "Trap Door"with Audio can be set preventatively to catch birds when they first arrive (before they build nests and find food and water). The Audio Module is powered by three AA batteries (included) which will last 4-7 days.