Thanks Jim and Greg for the post.
It is bad news for me though. I was planning on setting up for the
Richardson's that I visit twice a year with recordings at 24/96. But
from playing more with bats I seem to be limited to about 41,000
cycles with my equipment. I will still give it a go in the spring as
you recall the people alarm calls I recorded of this guy were audible
although narrow and short.
It is good to note that there is very little background noise up at
40,000 so a parabolic really is not needed for recording bats. The
lowest echolocation call I have captured to date was down at 16,000
which I just accidentally captured while recording at 44.1.
Rich
ps, this is a big gopher.
--- In "Jim Morgan" <>
wrote:
> The following message has been posted by Jim Morgan for Greg Clark,
a Nature Recordists member, that is having temporary posting
dificulities.
>
>
>
> In the 29 July 2004 issue of "Nature" there is an article
concerning an
> ultrasonic alarm call for Richardson's ground squirrel
(Spermophilus
> richardsonii) (The authors refer to Canada in the article) . The
alarm call
> frequency is very narrow, close to 50khz, and short, only 238 ms.
The
> authors comment "To our knowledge, ultrasonic alarm calls have not
> previously been detected in any animal group, despite their twin
advantages
> of being highly directional and inaudible to key predators." The
authors
> used playback and a pure tone at the dominant call frequency (along
with
> other control tones) to investigate the behavior of the squirrels.
The pure
> tone elicited "vigilant" behavior similar to the native call.
>
> I have two species of ground-dwelling squirrel that live in my
backyard in
> Arizona and I have a means of down-sampling the high frequencies so
that I
> can detect them. Perhaps I will hear a short click when the
squirrels see
> me. Those of us who have the means to detect ultrasonic signals,
and are
> around squirrels (especially ground squirrels) probably should have
a
> listen for these frequencies in case they are found in other
squirrels.
>
> I don't have a transducer that would transmit ultrasonic tones, but
this
> might be another way to see if the squirrels take notice. I imagine
the
> dogs in the neighborhood would be interested.
>
> Greg Clark
>
>
> [Non-text portions of this message have been removed]
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