These window stickers make an important contribution to the protection of birds around the house by preventing collisions with the window. An estimated 250,000 people die every day in Europe from crashing into a window. The exact number cannot be calculated, because most birds do not die immediately on the spot, but only later silently succumb to their serious internal injuries. During the breeding season, not only the injured animals are affected, but also their offspring that are no longer fed. A whole range of bird species are involved, such as blackbirds, tits, robins, sparrows, woodpeckers and many others. A danger to birds are all types of glass surfaces from small and large windows to wind shelters, glass corners, winter gardens, greenhouses, bicycle sheds and many other locations where glass or mirrors are incorporated. The glass reflects the surroundings with the blue sky and the vegetation of the garden so that the birds get the impression that the garden continues. The sizes of the birds vary from 10 to 25 cm.