bird control
Any system or device installed to prevent birds from roosting or entering a structure or area.
Bird control is any system, barrier, or device installed on an object to prevent birds from roosting, nesting, walking on, or entering the object. These include small spikes, jagged glass or ceramic plates, low-voltage electric wire or tracks, and ultrasonic emitters designed to discourage birds. The main purpose of these is normally to prevent bird droppings, such as from pigeons.
This feature does not apply to bird-proof windows, which are designed to protect birds from flying into windows and colliding with the glass.
The device is installed to discourage birds from occupying or entering the object. This purpose distinguishes it from glazing intended to prevent collisions: keeping birds away from a roosting place and making a window less hazardous to a flying bird are different functions.