Worn Out Retread wrote:
Does anyone have experience in using ultrasonic bird repellers? Do they
work or are they just a fancy gadget that actually does very little or
nothing?
....

HIGH FREQUENCY SOUND DEVICES LACK EFFICACY IN REPELLING BIRDS

WILLIAM A. ERICKSON1 and REX E. MARSH, Wildlife and Fisheries Biology,
University of California, Davis,California 95616.

TERRELL P. SALMON, Division of Agriculture and Natural Resources,
University of California, Davis, California 95616.

ABSTRACT: Ultrasonic or high-frequency sound-producing devices are
marketed as a scaring or frightening method for bird control. Although
inaudible to humans, most birds also do not hear in the ultrasonic
frequency ranges of above 20,000 Hz, thus the credibility of advertised
claims raises questions. A review of efficacy studies conducted and
published by a number of researchers fails to demonstrate the usefulness
of such bird control devices.

Proc. 15th Vertebrate Pest Conf, (J. E. Borrecco & R. E. Marsh,
Editors) Published at University of Calif., Davis. 1992

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