I made a couple of hour-long recordings last week at Rockefeller Wildlife
Refuge on the Louisiana coast. I am a rookie at this, and am curious about
the start-stop pattern to the calling (bullfrogs, cricket, and leopard
frogs, at least, I think). When I look at the waveform it looks "periodic"
at least in parts of the 75 min recording (See
http://www.geojeff.org/tmp_rockefeller.html). There certainly aren't any
long quiet intervals. Cricket frogs are the common callers at each
This recording was made at an egret/heron rookery near the headquarters of
From: Walter Knapp
Sent: Friday, April 19, 2002 11:59 AM
Subject: Re: [Nature Recordists] Vocalization intensity and speciesdensity
Doug Von Gausig wrote:
> At 08:04 PM 4/18/2002, Mark Oberle wrote:
> >Although it might make sense, I could only find a few papers arguing
> >at low densities, such as at the edge of their range, species might
> >to vocalize less than at higher population densities, with a lot of
> >rivals nearby. Does anyone have any similar or counter impressions?
> My observation is that most Passerines are stimulated to sing by other
> birds singing near them. Not just by their own species, either . In fact
> they are often stimulated to sing by almost any other sound - which is
> so many good recordings are made just as airplanes fly by!
Frogs do the same thing, sing like mad while the truck or car passes,
then clam up when it gets quiet again. Very annoying sometimes. I swear
I hear little tiny laughter in the quiet periods, that they are doing it
on purpose because I'm trying to record....
They have scouts that watch and when you press the record they signal
quick quiet to everybody. Then when you hit stop they signal all clear....
Then there is the other game. Sit quiet as the recorder runs on and on.
Then time it so that just before you give up and stop they call.
Briefly. It's a experiment they are conducting to see just how little
they can call and still have that hairless ape keep trying to record
On a slightly more serious note, frogs are definitely stimulated to call
by others calling. So you get much more continuous calling once the
population reaches a certain density.
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