Bird Gard Pro Sonic Bird Repeller for 1.5 Acres - General/Agricultural Comes with one built in speaker and repels birds in a space up to 1 acre. Crystal-Clear Digital Sounds with many Pre-recorded Configurations The built in amplifier and speaker are durable and the unit easily mounts to a fence or post courtesy of the included mounting bracket. Comes with a chip to repel European starlings, American robins, house finches, ring-billed gulls, common grackles, blue jays and red winged blackbirds. Repel targeted birds from crops, buildings, airports - anywhere birds are a nuisance.