The ads for ultrasonic bird and rodent (and even insect) control
devices appear everywhere, yet, try as I might, I can't find a
single scientific, controlled study on the effectiveness of these
devices.  A number of people have told me that the devices work
for a few weeks or months, until the intended victims grow accustomed
to the sound, and then they are no longer effective.
 
If anyone out there in Museum-L land has a reference of a study
where ultrasonic devices were show to be effective or ineffective,
please post it.  It would be such a nice world if only these devices
would really work!
 
John Simmons
Collections Manager
Museum of Natural History
University of Kansas