> Went to an interesting research talk this week on acoustics "caterpillars=
talk, butterflies listen" by Jayne Yack. While many moths can hear, only=
a few butterflies can. It was once believed that butterflies could not he=
ar and they were/are used as a symbol by some deaf communities. The moths a=
re able to hear the calls of bats.
Chad,
When I got involved in bat conservation, I discovered the new world of
ultrasound. Normally we are not aware of this but even a cheap heterodyne
bat detector opens up this whole new soundscape. First off you often find
ultrasonic crickets interfering with the bat calls and also hear the high
harmonics many songbirds produce in their calls.
Ciel make a stereo heterodyne detector which is a bit awkward to use but it=
gives interesting results. I am currently studying horseshoe bats which pee=
p
rather than click (CF calls as opposed to FM) and they warble when flying
due to the Doppler shifts which are exaggerated by the heterodyne frequency=
shift.
For more info look at Wikipedia "Bat detector" (which I expanded some time=
ago) for the different types.
David Brinicombe
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