Ultrasonic sound waves do not mimic natural animal sounds like sonic repellent devices do, so it is not targeted to specific pest types. Instead, ultrasonic sound waves (which are above the human hearing range, thus silent to us) annoy & irritate pest animals into leaving. It is thus effective against ALL birds & small pests. If you have very small birds such as sparrows, it is recommended the device is set to constant instead of motion-activated (there is a control switch to change this setting). Larger birds such as pigeons are more likely to set off the motion-activated sensor.