US Patent 7487737 Whistle structures

Devices that emit sound audible to nearby animals can include a deflection structure or other support structure and, connected to it, at least one whistle structure. The deflection structure can, for example, be a rain guard, an insect deflector, or a rock deflector. It can, for example, have an air flow surface across which air flows when the vehicle on which it is mounted moves at normal operating speeds, and whistle structures can be activated by the air flow.