The Trap Door provides a discreet, gentle, hygienic and cost-effective way to get small birds out of buildings. When set, the Trap Door is 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. You can add a proprietary sparrow song, which has proven to attract more birds, the company says. When a bird is captured, it will remain within the holding box until it can be released safely outdoors. Food and water can be left inside to protect the bird.