Tested & proven effective against pigeons seagulls & smaller birds Timer on constant setting can be set from 5 to 30 minutes delay with adjustable volume control Can be set to motion-sensitive PIR or constant Effective range of up to 1 acre when the volume is on full Built-in photocell disables the device in the dark The sound of hawks & owls may also scare away rodents such as rats & mice Power supply included This Electronic Bird Scarer uses the hunting calls of a sparrowhawk falcons & owls to frighten other birds away